Fastmail allows sending from any address, the client supports it easily. There is also a few self-hostable mail clients that allow it.
Historically I used a more convoluted method. When I used to use migadu (dont use them) I had a little script that would check the first line of any email I sent myself for a target email and resend it from the receive address. It was janky but worked.
Here is a fullish comment thread involving me and a migadu employee on the matter. Note he still claims some kind of email was sent at the end (it wasn't). https://news.ycombinator.com/item?id=24974369
There are a few other threads on HN about them as well.
Essentially they are a bargain basement supplier and expect them to treat you as accordingly. If you're happy with that then its fine!
Historically I used a more convoluted method. When I used to use migadu (dont use them) I had a little script that would check the first line of any email I sent myself for a target email and resend it from the receive address. It was janky but worked.