@makuru if you use your domain without subdomain and interact with some peoples, your fedi software will generate a key to sign your stuff and when you throw away the db, you wont be able to delete those messages ever. Beside of that, fedi softwares in general do have issues when you suddenly change yours / when you reuse a domain.

So try softwares out on subdomains, when you think you are happy with one, use it without subdomains or keep using the subdomain