Oh yeah, my Logic for Mac is probably about that age too, but there's no choice to buy it outright on iPad sadly.
Oh, didn't know that. That's lame.
I could see using an iPad for automation, triggered by midi, but I use an Air for that (and even if I used an my Pro, I still have to use a USB C hub because for some reason Apple things 1 (or 2) USB ports is enough. Sigh.
I bought a license for Pixelmator Pro a couple of years ago. IIRC it cost 30 or 40 EUR. I don't use it much, but it is unlikely you're going to need all of that software.