For the foreseeable future with Lemmy, plan on the unplanned.

Create accounts on several instances, and keep them synced.

I use lemmy-account-sync. It works perfectly for me.

There's another project, lemmy_handshake, which is an Android app (YMMV, I haven't tried it.)

It's not too difficult to use Oracle's free tier and Lemmy-Easy-Deploy if you want to register a domain and set up your own single-user instance. I do that, knowing that it could poof at any time. I run lemmy-account-sync as a cron job nightly on the same Oracle instance, but hosting your own instance isn't required for syncing.

I sync my main account with accounts on a few small instances. I chose them from the list of Lemmy nodes which are on the current version of Lemmy, that have active users. Small instances tend not to defederate other instances so much, if that is important to you. They are also less likely to be targets of DDOS attacks. They can also wink out of existence without warning, which may be the case with lemmy.villa-straylight.social.

I also sync my main account with accounts on a few of the larger instances. (I mainly use Lemmy Explorer to find Communities, but big instances are best if you just want to doom scroll "All.")

Should I tire of self-hosting, or if Oracle decides to randomly delete my instance (a real risk), then I'll just log into another instance.

You'll lose some stuff (like post history, and private messages) but it will be better than losing everything again.