Much as I love the '85 it's getting old and isn't the easiest thing in the world if you've only used Arduinos. In particular, the lack of a serial port makes debugging quite tricky
You might take a look at the newer ATTiny devices which are better & cheaper.
I confess a minor commercial interest here!
I use & sell a ATTiny1614 board. attiny
Spend some time reading over the attiny core GitHub home page that was linked. Spence has each supported chip explained in great detail along with the pinout images. I find those images very useful for figuring out how I’m going implement a particular idea. Sometimes it’s more of a “can I do this” check with the i/o configuration for each variant. It is a very well documented, high performance core. Be sure to check out his boards on Tindie