Unfortunately, no.
Currently, activitypub identity is tied to domain name. While mastodon support migration as long as the old domain is still up during the migration process, AFAIK Lemmy doesn't even have a process to migrate an instance to a new domain yet.
So basically, if you switch your instance domain, you'll mess up all your federation network, unless Lemmy devs implement a solution soon.
Somewhat related. Basically, the management of the .ml TLD are being handed back to Mali government, and they seem to revoking.ml domains left and right.
I suspect they're revoking registration for .ml domains that was registered for free. the company that originally managed .ml domains had a free domain offers where you could register any .ml domain for free, the caveat is you don't have the ownership right to that free domain. Maybe Mali government doesn't honor such free domain registration and wish to revoke them all.