That does seem like a good option for my use case, interestingly they note that no matter what I switch to I should change the subdomain:

It’s not supported across the Fediverse to switch between implementations on the same domain. This means that if you run GoToSocial on example.org, you’ll run into federation issues if you try to switch to a different implementation like Pleroma/Akkoma, Misskey/Calckey etc.

That doesn’t look promising for moving the account without migrating because then I couldn’t maintain my username.