ActivityPub acts like two-way RSS
Why do you want sub-accounts, if you can have as many regular accounts as you want?
Websites can be bridged to ActivityPub with https://fed.brid.gy
Yes, hiring more IT security specialists
Oh, can you pm me (@cyber:sysrq.in)? I can’t get mautrix-telegram bridge working, it doesn’t respond to invites from rooms on other servers.
Expect AP updates to be rare, just like other protocols
Friendica, Smithereen or Hubzilla