good question but for the android based tv's you can plug any common cheap cable mouse see photo mine is just an old 10 year old or more !! Microsoft cable mouse right of image or you can use the tv remote can you see the two mouse pointers which I learnt later you can turn of the remote control cursor.
if you have a touch screen version then it gets real smart
its worth noting if your using android tv then use the puffin browser from the App Store it basically goes full screen without any tabs or url bars etc..there is also firefox tv version im working on now which renders css a bit different from the standard or common firefox download but ill nail it within a few days .
chrome for android tv just has a whacking great big toolbar thats permanent ..
samsung tv's only success I had was on a 2019 model we have two others based on I think 2014-16 circa and a 2017 circa both have no browser updates available through the Samsung App Store so a bit of inconsistency between brands and models .
best so far has been android tv seems to conform reasonably well for the purpose. its definitely an eye opener if you can justify a 32" size for the purpose . I quite like it shame I bought it for our guest room definitely toying on getting another if I see one at a reasonable price ..Brian