This sends me on a rabbithole to discover new top level domains (.org .com .world) are added in rounds. The last one was in 2012. The next is NEXT YEAR.
Would be amazing if we could get .lemmy but it would be hella expensive. $185k for application and 25k annually to keep it. Not sure if we can crowdsource such.
Blackjackandhookers.online and .community are still available though.
This does include .co.uk .org.uk but the reason those exist is because you could not claim a pure .uk cTDL before 2014 because and this is an important piece of information for anyone looking to get a domain name. Countries can set the rules for their domain themselves; There have been instances (fmhy.ml) of governments revoking a registered domain, in this case because they discussed piracy.