I think that it’s great that you can find some use for it! Hopefully even after you upgrade you can continue to use it in some capacity if that’s what you choose.
I have a 9.7-inch iPad Pro (probably my favourite iPad ever), and since it runs iOS 12 there’s a part of my content consumption requirements that just doesn’t work, but enough works so as to make it a good sporadic iPad, so it still sees some use. Battery life is still rather fine barring the loss vs iOS 9 (30%), so it can be used for about 10.5 hours of light use, perfectly fine. I have certain tasks for it though. For example, web browsing is tough.
The A16 is good so you should have no problem with the 12th-gen. Here’s hoping you can get it!