Posteo seems like the only good option there... Sadly they don't allow custom domains because of some hand-wavy "privacy" crap that boils down mostly to vendor lock-in like tuta.

There is a new belgian co-op company Nubo trying to break into the market, but they are tiny and running a nextcloud instance on-prem for storage. Performance is likely to not be great.

I've been using Startmail for a while now. I'm not sure if it has a drive function because I never looked for that, but it does let you create an unlimited number of semipermanent and temporary 'alias' email addresses, and you can use a custom domain, if you set one up

If all you need is solid email hosting, I can vouch for Migadu. I've been using them for years with my own domains. Been perfectly reliable at reasonable costs.