Welcome back! Universal Bluetooth keyboards should work on any Android device, although cheaper keyboards might not work as well. A while ago, I got a cheap Targus keyboard that would connect fine, but when using it, it would constantly enter some kind of sleep mode if no key was pressed for about 5 seconds. It would come out of this sleep once a key was pressed, but there would be a half second delay at first, which would always cause repeated or skipped keypresses. Very poor design. On the other hand, an Acer keyboard I had worked much better. So if you're going to get a keyboard, stick with well-known brands like Logitech.
Bluetooth keyboards designed for iOS devices should still work on Android devices, but of course, the special keys meant for iOS won't do anything on an Android device.