Skyway
You were right; I tried downloading the Florisboard and it worked - I was finally able to switch to another keyboard! I also know now why I couldn't make it work with my former keyboard app:
I tried yet again to download/install the keyboard/language app I've been using for years (From F-Droid) but it wouldn't work on the new 2023100800 release. Turns out that what I had downloaded instead was a language pack that used to include the AnySoftKeyboard keyboard as well. But I think they've divided the two because the instructions in the app info now said to make sure to download and install the AnySoftKeyboard keyboard as well in order for the language pack to work.
I should have paid more attention then none of this would have been an issue to begin with - sorry for the inconvenience and confusion on my part, guys!