For one thing, if you want to go the breaker route, you can get GFCI breakers for your existing box (just make sure you match manufacturers because breaker panels aren't standardized. A Square D breaker won't fit in an Eaton panel). This adds GFCI protection to every receptacle on the circuit but does require you to identify the neutral wire for that circuit and move it to the breaker.

If you go this way though, you are further investing yourself into that manufacturer's ecosystem.

The GFCI receptacle adds protection to the receptacles down the line. It also adds the benefit of having the test and reset buttons in a convenient location. This does require you to determine which receptacle is 'first' in the chain. So you don't need to replace every receptacle on the circuit to have the protection.

I hope this helps. FWIW, I am not a licensed commercial electrician. I deal with electrical supply professionally, but it is all temporary distribution, so we don't deal with the same codes and all of the infrastructure is in the open.

Are you sure they aren't already downstream of another GFCI device? Personally, I would pick up an inexpensive outlet tester like this one to verify there isn't protection. Pushing the test button simulates a ground fault which would trip a GFCI device. I also would not worry about adding an AFCI receptacle. AFCI breakers protect the whole circuit and can be installed during a later panel upgrade.

If you've verified there isn't a GFCI upstream, you can use the outlet tester to check which outlet is first on the line by disconnecting one (turn off breaker, cap off the wires, turn breaker back on) and seeing if the other is still live. The GFCI receptacle will replace the first outlet, the feed wires will land on the terminal screws marked "line" (usually the top), and the wires feeding downstream devices will be landed on the terminal screws marked "load" (usually the bottom screws).

To add to the other answers:

Many jurisdictions require you to add AFCI protection whenever you replace an outlet in an AFCI-required area (which is now most of the house, and I'd expect bathrooms to be added before long). The best way to solve all your problems is GFCI/AFCI breakers for those circuits, but you may have problems finding those affordably (or at all) for some old panels.

Note that AFCI receptacles work like GFCIs in that they'll protect everything downstream, so if you don't or can't go the breaker route, it might be worth it to find the first outlet on the circuit via trial-and-error and just swap that one with a combo outlet.

If you have to prioritize financially, always take care of GFCIs first. That's life safety.

So here is the thing. A house from that era may have aluminum wires( and even if copper the workmanship was shit back then.

Been working on older houses like this for 40 years as a reno carpenter. I know all the basics but do I do it? No. We only have qualified electricians do the work. The same with gas fitting or plumbing.

I'm ok with DIY but know when to say when. Sorry but a house of that vintage needs a good go over by a pro.

There are zero GFCI outlets or breakers in this house. Built in the mid-70's, no major renovations other than a really cruddy tile floor that at least was more attractive than the mustard yellow vinyl tile that was under the carpet sections I yanked.

For example, I just took down a hard-wired smoke alarm dated 1975. Who knows how long since it's worked but I'm just now getting to evaluating any electrical boxes I didn't install. The hard-wired ADT system is about to get the can. I just found the control box today (in the pantry, had always thought it went to the phone) and the battery has been disconnected for who knows how long but I'm going to search and make sure there's not a transformer plugged into an outlet somewhere (it may be long gone) before I yank stuff from the wall, tape the wires and push them into the wall so I can repair them.

Thank you for the good reminder. The wiring is copper, I know that much from the small amount of wiring work I helped my ex do. It was a house from a major builder at the time so I do and don't trust the wiring.

But I do have a list started for an electrician when I have the money of things that I can't handle. I would like a few new outlets placed and that's WAY outside my expertise. And the entire breaker box needing to be replaced. I wouldn't even touch that. I'm going to ask them when they're working if anything looks like it needs to be upgraded.

But replacing outlets/switches and light fixtures are the extent of what I feel I can handle. I can't afford to get a handyman or electrician to do all the little jobs. I haven't done a lot myself but I was always the helper with my dad and my ex and I'm aware of safety. I'm replacing the doorbell transformer this week or next weekend when it comes in so I can put in the video doorbell. But the fluorescent lights flickering in the kitchen, no. Might be as simple as replacing a ballast or starter but I'm just not confident since it's already flickering.

I thought AFCIs were only required in multi-unit residential buildings.

Nope. They're required in basically all dwellings now. There are like two rooms left where they're not mandatory, and I expect those exceptions will disappear soon.

Sounds like the guy who invented them must be in with somebody at NFPA

Often switching to an AFCI/GFCI combo breaker is cheaper, depends on the setup.

Disconnecting the outlets and testing them live will indicate downstream, just mark the live ones with tape.

Keep in mind AFCI and GFCI breakers will only work if the neutral isn't shared by any other circuit, which in many cases they are.

The conspiracy theories abound on electrician forums, let me tell you.