Is it really worth your time forking it to remove licence checks, when you could instead support the developers and not need to make any code changes?

Forking the code and removing licencing checks is perfectly permissible under the GPL. But it's pretty unreasonable in this case.

> but it seems to have some license purchase requirements even for the self-hosted options

which doesn't appear to be completely true, regardless of whether you think it's worth your time or or reasonable.

The license check is relatively easy to bypass, and there are also forks and reimplementations out there that already do so.