Nope. If the post is like "/@:user/posts/:id" rewrite it to "https://mostr.pub/objects/:id" I will improve fediverse interop soon.
What is the bunker url I need to sign into mastodon apps?
In theory any nip46 signer, but the only perfect one right now is a command line tool called nak: https://github.com/fiatjaf/nak Eventually I'll improve this situation, but Mastodon apps besides Soapbox are mostly a cool tech demo, so it's more of a side quest.