So activitypub plugin does seem to work with #ClassicPress. I dont see the customization options in a metabox like in gutenberg editor, but I’m not too fussed about that.
The one thing keeping me from migrating from WordPress to ClassicPress is the excellent ActivityPub plugin.
Its great, but i wish i had the time to port all the broken parts to the ClassicPress way of doing things i.e. the WP things that have changed since 4.9