@DavidMStraub announced the launch of GrampsHub in July 2023. It is a managed GrampsWeb hosting service.
@hartenthaler, posting your initial support question here (in the GrampsWeb category of the Gramps Discourse community support forum) is fine. No need to worry about whether the issue is in Gramps, GrampsWeb or GrampsHub.
This Discourse forum is the best place for newbie questions. We can connect you to the right place in the complex ecosystem of Support options. And will do some handholding along the way. (This is the easiest place to share screen captures too!)
David will followup on the issues related to GrampsWeb or GrampsHub pieces. (Hopefully, more users will become familiar enough with GrampWeb idiosyncrasies over time. There are already a couple who answer the occasional question. Then he will have less stress answering questions. Which means he has more time to enhance Gramps Web.) And users familiar with Gramps will chime in on those issues.
I noticed that you posted a cascade of questions on GitHub. Then David noted some as Gramps issues… like import of GEDCOM dialects. I’ll try to go through those and cross-post here to Discourse as appropriate today.
I strongly recommend that you install the desktop version of Gramps locally and use it in combination with GrampsWeb on the GrampsHub hosting service. With shared development going back to 2001, the original desktop version of Gramps is more mature than the GrampsWeb fork. It has more features and tools for data manipulation.
The Gramps Web Sync addon allows to keep your public collaborative tree in sync with your private experimental tree.