Honestly, as someone who was content and happy with the OP5, Pixel 7 is a bit too much of an upgrade for me. (Ultimately chose 7 because I found a better deal at that time.) If you can find someone who has the 5a or go in a store and try it out, that might help your decision-making.

I also have an OP5, but just bought a Google Pixel 7 because OnePlus just isn’t a flagship killer brand anymore. Their phones have gotten too expensive for their quality.