https://support.apple.com/en-us/HT210425
No one would dare block @icloud.com.
Also have you consider plus addresses or . addresses ("." is preferred if your email provider supports it -- harder to assume that you can just remove the dots for downstream spammers).
[EDIT] Did some quick searching, and the F/OSS community has delivered! There are at least two you could use:
https://github.com/foxcpp/maddy
https://blitiri.com.ar/p/chasquid/
They're simpler, and maddy (at least) has an S3 backend now.
Point being that I image many mail providers offer such a thing
Here's a video demo of the inbox for your domain @ https://www.youtube.com/watch?v=EyBIpO5VkLk
Alternatively just set up catch-all on your existing email for the domain, no extra apps needed.
A domain + Cloudflare Email Forwarding (with catch-all)
or
A domain + Catch-all on my GSuite (or Workspace, whatever it's called now...) subscription