Also it's not ready if i have still to complete something. So maybe "Almost ready"

Depends on the outcome for sample data and extra languages, there is a debate to completely remove them from the installer

Also it's not ready if i have still to complete something. So maybe "Almost ready" ?

Technically it is ready. The site's usable, there are just some optional extras you can add with the languages and sample data. And unless we're going to add more conditional logic to detect when we actually enforce the "remove install directory" check, I don't think we need it to say "almost ready".

Then we don't need a complete because it's complete?

depends on if you think of it as an adjective or a verb? ;)

eg
To complete the site open the admin
The site is complete you can now open the admin

Personally as the title is already saying "your site is ready" then you only need "Open Site" and "Open Administrator"

Note it is Administrator not admin see style guide

So if the installation folder is still there it's definetly not complete for most of the users.
Is that option just on staging versions or always?

It's always there.

Removing it is not a requirement unless the version class is set to a stable release, which only happens when we are building the release packages. When running from the git repo, it's not enforced.

@brianteeman May we go with Open site and Open admin options instead of using Complete. I have understood it I may create a PR for this if it sounds good.

@coolcat-creations Does PR #35988 solve it for you? Or should there be done more?

As far as I can see the PR solves only a part of it, i.e. it still leaves 2 buttons.

I'm happy to take pull requests to improve the installer at any point. But going to close this for now as it's unlikely anything more is going to happen here given it's sat here for 3 years with no PRs and there's no clear proposals on how to improve the UX further.