I switched to migadu which was not too painful for a single account (basically the advice was to put both accounts in thunderbird and then move everything over, thunderbird does the work). For email very happy with the provider, notably also as it allows infinite domains.

But I miss a proper calendar which migadu is strangely mostly lacking (basic caldav only). Is fastmail better in this respect? And can you do wildcard emails and send/receive as whichever name you want with fastmail? E.g. I have it set so every email which comes to xyz@domain.com arrives in my single inbox (so not catchall but all with a certain letter combo) and use this to have custom emails for every site.