Grayjay Desktop App

Recommending (and running) `xattr -c` can be extremely dangerous. I would suggest withholding Mac releases until they can be distributed/run safely.

As someone not very familiar, is there any legitimate reason why they say "Our Apple signing/notarization is not entirely done yet"?

It feels extremely suspicious, given that I download lots of other popular utility software from independent devs and I've never had to do that before.

There are a couple of legitimate reasons, namely the expense/KYC process of an Apple Developer Program membership and/or the complexity of integrating signing + notarization into existing build pipelines (but XCode does makes it pretty straightforward to cut an ad-hoc release that is signed and notarized).

In my opinion at least, the most likely reason is that Apple is refusing to notarize the software. If this is the case, people really should not be running it.

Once you buy a Mac, Apple doesn't own it anymore, so them not wanting you to run a piece of software isn't a good reason why you shouldn't.