I'd use it for some light browsing, gaming, reading in IT books, watching some TV in bed.
Testing self-made apps too.
As others have said, the Mini will do those things just fine. Over the past 5 years, I've gone from the 1st gen 12.9 iPad Pro, to 6th gen iPad, to the Mini 5... and with each change, I'm using the iPad more than before.
When I owned the 12.9 Pro, I ended up getting a Mini 4 to use for those times when the 12.9 was too large. I replaced the 12.9 Pro with the 6th gen iPad because I heavily use the Apple Pencil and the 9.7" iPad was a better size for using it as a digital notebook.
I then traded in the 6th gen and Mini 4 for the 5 because I was using the Mini more than the iPad and needed Pencil support. The Mini 5 is the same size as the paper padfolio that I used (1/2 US letter size)
I use it as an ereader (books, comics, vintage catalogs and magazines), music player, DJ mixing, onboard video playback and streaming TV, digital notebook, mini chromebook, puzzle games, zoom conferencing, and a ton of other stuff.
It's a beastly little device.