I'm not the poster you're replying to, but i did the same thing and use Purelymail (and their web interface, which i think is open-source)
it's a very cheap no-nonsense service, i recommend it
Over the years I've recommended Migadu and still do. Affordable and reliable with usage based pricing.
As for the email client I personally prefer Thunderbird on PC and FairEmail on Android.
Also not the poster you're replying to, but I get email with ProtonVPN, which I've linked to my domain.
I'm not without my questions about them as a company, but Google are getting beyond a joke.
Full migration away is coming with next phone upgrade.
+1 for Purelymail. Most things that appear to be too good to be true are not true. Purelymail is the real deal.
I just signed up given the low price, got it setup with K-9 POP on my phone. Gotta say that is a very simple and easy to follow setup. Compared with something like Zoho where I get lost everytime I need to navigate around.
I'm really liking this, thanks for the recommendation.