The Bluetooth mode is made specifically for the Nintendo Switch on that model, on PC and Android you need X-Input mode, which is made available through 2.4GHz and USB-C.

I complained about that part too, and 8bitdo doesn't seem receptive..

To configure the controller you need the software here.

In response to your header: Play games with it. :P

I wouldn't recommend Bluetooth as a first choice for connectivity, is there any reason you don't want to use the included wireless adapter?

As for games, I have no idea what you like/don't like. How potato of a PC are you using? FWIW some lower spec games I've played in the past several years with a controller included Cat Quest I and II, as well as the two South Park RPGs. There are also some fun co-op games like Overcooked, Moving Out and Unrailed. Overcooked really spawned a bunch of frantic co-op games that are low-spec and controller-friendly, so you can check that genre out as wlel.

I don't have an 8bitdo Ultimate controller, but I have several of their other ones. They all work for me over bluetooth when I pair it with my PC and then use Steam to recognize the controller. They show up as a Switch Pro controller, meaning Steam won't be aware of the back buttons (I'm guessing you need to use 8bitdo's software to do that). But you can remap the regular buttons and the gyroscope in Steam's UI. If you use xinput mode, then you are limited to the controls on an Xbox controller, so no gyroscope.

That does mean you need to use Steam to launch all of your games, even if you bought them elsewhere, but Steam has a controller-friendly interface, so I prefer to do that anyway.

edit: Bah, I just saw @mp3's comment. Too bad that their Ultimate controller doesn't work like their other ones, that's a big step backwards.

You’ll need to download their software to map the rear keys/tweak anything else. They also have a phone app that does the same thing if you didn’t want to install it on your computer

I should add that I'm open to Android games as well.