>Because android sms is unencrypted

No. SMS are simply not encrypted regardless of whether you send them from an iOS device or an android device.

If you message on an android phone with someone else with an android phone it wont use standard SMS but instead use RCS and this is encrypted.

This is the same as using an iPhone with iMessage when texting another device supporting iMessage. The fact that iPhones and Androids don't have encrypted texts between them is due to Apple not supporting RCS fully.

rooting your phone/unlocking the bootloader is VERY different from what people usually consider an "unlocked phone".

"locked" / "unlocked" in this regard is just about carrier locks like they are common in the US. Buying a phone through a carrier and the phone only working on that carriers network and it coming with preinstalled apps and receiving its updates through the carrier.

Buying a phone off for example amazon on the other hand will (afaik, in my country locked phones are illegal) have the phone "unlocked" -> not locked to any carrier -> only the "Samsung" preinstalled apps on it.
This will NOT trigger any KNOX protection like rooting your phone would, so your banking apps and yes the McDonalds app will work perfectly fine.

I like it here in Hamburg and surrounding area. The by far largest issue with it were the prices (several hundreds euro per month for some of the tickets). That point has been solved. 49€ is cheaper than the cheapest available monthly ticket just for the city of Hamburg so far.

Around here in Hamburg and surrounding area it actually got a lot better in recent years.