It's rather confusing what you need now, and the steps to make this work. I looked into it a while ago and apparently Altistore would only work on an old version of IOS, and UTM with full virtualization (what you have to have for anything decent) wouldn't work without tethering.
UTM is ok, but Apple sabotages it on the iPad blocking access to the hypervisor, which is a part of your processor that translates instructions dynamically.
Also, Apple will actively hunt for those apps and revoke their license, which means you have to constantly reinstall them.
If there's a good way of doing this, we need a manual. If for some reason 17 now is making this a good option (it wasn't before IMO, just a hack), then we really need instructions.
Apple has made it clear they are set against this sort of thing. They want us to believe that iOS is more secure than Mac OS. Well.....
It is a fun sort of thing though. But as someone said, Parallels on an iPAD? Now that would be something
Yes, they are against virtualization / emulation. Which is too bad, because Apple devices can do wonders with emulation.
If Parallels really wanted, they could develop a cloud app to bypass Apple's license. But it's too much of a hassle for too little benefit. Like I said before, Apple's advantage on portable devices is running thin, and you're probably better off with a Surface or a x86 portable device, which will give you a better run for your money.