You wouldn't want to port it. There are a billion icons and toolbars which won't fit on the ipad. The whole thing would have to be redesigned from the ground up with a UI similar to procreate that keeps the main canvas free from UI.
And if you put in that much effort, you are going to want to charge for the app. Understandably, iPadOS doesn't have a thriving open source / free culture.
That’s a pretty big ask on a technical level, i’d be very surprised to see that happen anytime soon.
If you’re looking to get out of the adobe ecosystem i’ve had a pretty positive experience using Affinity Designer on my ipad (no affiliation with either company).
Wacom has some much cheaper Cintiq displays these days. I think it's $350 for the 13" and $650 for the 16". I got the 16" recently to update from an old Intuos that finally gave up the ghost after 15 years. The texture of the stylus on the display is a lot better than an Apple Pencil on an iPad, even with a silicon tip (which I also have).
Just bear in mind that the cheaper Wacom displays are not glass screens. I have the 16" cintiq (not pro) and the screen has a few scratches in it already.
The biggest advantage for me is the actual Wacom pen, which was designed to be held and used for a long time comfortably. The apple pencil is ok but I need something with a thicker grip and putting a pencil grip on the apple pencil covers the two touch buttons and stops you from recharging it.
I still have and use an iPad pro with apple pencil 2 but the Wacom pen is 1000x better.
If you are doing drawing, you should give this a chance: https://concepts.app/en/ free version is very good on Windows. But their main platform seems to be Apple devices.
