Adding contexts in D9

I'm trying to create a page that will show a node form (contact formular), but in D9 it seems a lot is missing or not working.

Adding a context doesn't seem to work, i can select something from the dropdown, but when adding it i will always get the same formular with label, description and context-value or entity-selection. In D7 this always was specific to the type of context, such as node_add_form and checkboxes of the content type, this is completely missing here.

Regardless what i type into context-value or the entity-selection input it gives no results or returns an error.

This might be related to the contexts missing, but also when trying to add content there are only standard blocks available, in D7 there was a large set, including single fields, custom content with tokens etc. Filters are also very reduced, i would need to check for a query parameter in order to show a different variant.

Also: how can i add page parameters to a page? The only page that exists by default is node/{node} which has a parameter, when creating a custom page there is none, but also no UI for adding something.