Assuming you can get your hands on actual raw semaglutide and know what you are doing, absolutely. It's not rocket science, drug dealers do that all the time. Pill presses can be had on Alibaba for a few hundred bucks and you can order virtually anything from "research chemical" online stores as well.

But it is not risk free either. Contaminations of all kinds are the worst issue (particularly with anything supposed to be injected, so never try it with insulin...), but the most pressing one is agent distribution. That's what causes a lot of people to OD on stuff cut with fentanyl - if the fent, the actual drug (say, heroin) and the fillers aren't properly mixed, you may end up with a bunch of pills with far higher doses than intended while other pills essentially consist of pure filler.

If by compounding you mean producing semaglutide, no.

If you have a source to buy lyophilized semaglutide and some BAC water, you could certainly reconstitute it yourself and pick a dosage, or compound in some vitamin b12 or similar.

In practice for an average person, this means either buying them as research chemicals directly from china, or from resellers that mark it up by 10-50x. You might get a COA that testifies the chemical in question and it's purity level for that batch, and maybe that COA will actually match the batch in your vial. But you almost certainly won't get any guarantee on sterility. And there are reports of the contents of vials getting mislabeled, so people got entirely different products.

You can try to counter some of the sterility issues with filter syringes, etc., but you're only mitigating some risk, not eliminating it.

They're buying semaglutide salts from China and mixing it into distilled water. It's not that difficult. I wouldn't trust the sources to be pure and not doped with something else though. You're taking an even larger risk with an injectable.

There are a lot of bodybuilders using it to assist with cuts, yes. They're largely focused on retatrutide at the moment, though, since it seems to be more effective and they're a group that already is comfortable injecting themselves with substances they've acquiring from grey or black market sources.

It's great and I'm happy for you that you have a body that is such that you can do that. Many people do not have similar experiences. Often times people who are not able to do things like are labeled as having a lack of control or a failing in the character. The truth is that many people have different chemistry which makes doing something like this borderline impossible.