I just installed current master as of today, and am testing:

1. The docu mentions git bug ls, but is seems not to exist anymore. Is there an other way to list issues?
2. The docu mentions git bug bridge configure, but is seems not to exist anymore. -> I want to add a second bridge to a second github remote on a local repo. I opened .git/config, and copy&pasted the entry, editing the owner field accordingly; that seems to work somewhat, though when I push to this bridge, it pushed 0 issues (and there are no issues in the github UI), even though I have 54 open issues locally.
3. what is the difference between git bug push and git bug bridge push (and same for pull)? I know it, but purely from CLI help messages, I could not deduce it.
4. Is it possible to pull form one github remote/bridge and push to an other?
5. It is git bug help but git bug bridge --help

This is a dup of https://github.com/MichaelMure/git-bug/issues/1209 (or the other way around). CLI has been refreshed and the documentation hasn't followed yet.

Is it possible to pull form one github remote/bridge and push to an other?

No, git-bug prevent this (see https://github.com/MichaelMure/git-bug/issues/1223#issuecomment-2268697889) as it's almost always a bad idea. Possibly some special case could be carved out, but it wasn't the focus at the time.

Converting this to a Q&A discussion. The issue that was brought up -- outdated documentation -- will be tracked in #1209. To the remaining questions...

The docu mentions git bug ls, but is seems not to exist anymore. Is there an other way to list issues?

If you've built from HEAD, ls was moved under a bug subcommand, so (somewhat awkwardly), you need to type git-bug bug. git bug ls is still appropriate if you're using v0.8.0.

what is the difference between git bug push and git bug bridge push (and same for pull)? I know it, but purely from CLI help messages, I could not deduce it.

git-bug-push and git-bug-pull interact with refs/bugs namespace on the remote -- pushing and pulling like you to a branch under the refs/heads namespace.

git-bug-bridge-push and git-bug-bridge-pull interact with the bridge's API, and could more aptly be described as "import to git-bug" and "export from git-bug" operations. I agree that this experience can be improved. One thought I have is to make bridge operations transparent (#1223), but we could also provide better clarification via documentation and helptext.

It is git bug help but git bug bridge --help

Thanks for bringing this inconsistency up.