I have Gitlab-CE running (so far fine) on a company VPS which is running Almalinux10, but I installed the version compiled for Almalinux9, as there is none for Almalinux10 yet
Is this very dangerous? can upgrades be more susceptible to breaking because of this?
what about when the package compiled for Almalinux10 comes out, can I just install it, replacing my current installation, as a sort of upgrade?
I may be able to answer myself on this one… This is an unsupported configuration and I shoudn’t do it in production 
The Gitlab package contains pretty much everything it needs. I’ve done this a few times on Debian when a new release of Debian has come out and a Gitlab package hasn’t existed. Then you later switch the repo file over to use the new one when it’s released for EL10-based distros.
There are occasions when the Gitlab package does rely in certain OS dependencies, like perl for example and obviously if these don’t exist it won’t let you install/update the package anyway.
On Debian for example when switching to Debian 12 from 11, I had the Debian 11 package. When I switched the repo over to Debian 12, it updated with the Debian 12 package fine.
There is always a risk with it, so the real thing to do is simply wait until a package is released for EL10. Until that time, use EL9 with the Gitlab package. You can migrate it later to EL10 using the Gitlab backup/restore functionality as explained in the Gitlab docs. If you do use it on EL10 though, you will have to be careful when making update to the system, in case it removes something that you really need. It just means paying attention to the output on the server. In most cases it can be fine for a short period to run the EL9 package on EL10 distro, but you never know if something bad will happen. My experience so far has been fine, but that doesn’t mean it will be the same for you or anyone else. It might, it might not.
Alma does have the ELevate project which can upgrade EL9 to EL10 anyway, so you will have an easier method to migrate across than say clean install.
Awesome, thank you, I already changed to EL9 and installed it again. It’s great to know now that in the future I will be able to upgrade from EL9 to EL10 easily with that ELevate project 