Yes lemmy should be at 19.6 at least

It does, but the comments in that crosspost would be independent from the comments on the own community.

Yes. That's what the wordpress apub plugin does with lemmy

It's pretty straightforward. Just activate the plugin mostly. There isn't anything about audience in the plugin settings iirc so I'm not sure what you're seeing.

Don't have any experience with B2 myself. Have you considered another provider?

Are you using object storage or block storage?

Probably either pict-rs misconfig, or run out of space.

heh, sadly it doesn't prevent you seeing their opinions in comments. But still, it ensures that they won't ever appear in your own OPs.

There's another option to "block" an instance: if you make them ban you, they won't be able to see your posts or interact with you anymore.

For another, my emails look like emails everywhere, both on source and destination. I don't have a different character limit or feature set about what I can slap into my emails depending on what client I'm using, and I'm reasonably sure my email looks the same on the other end, no mater what client the recipient is using.

This is mostly the case now due to centralized email by a few providers and bountiful bandwidth, but it was certainly not the case 20+ years ago.

Also, not the part of Mastodon specifically that people didn't understand, they just tried to log in, were presented with a thousand instances, told choosing which one to use was super important but also that it didn't matter and they should keep changing instances later, but also that migrating instances was not an easy process, but don't worry, it's just like email.

People used to do the same with email before google and microsoft dominated email. It's just that in most cases, your ISP provided you with an email when you first signed up. Switching email provider currently is way more onerous than switching mastodon or lemmy providers. If each ISP nowadays hosten their own say, friendica server and provided you with a login immediately, it would have a similar effect of solving this difficulty of choosing.

There's absolutely no way this is sustainable

Copyright doesn't prevent this, FYI