Yes. Proton lets you use 1 domain for $4, or 3 domains for $10. Port87 is unlimited domains for $10.

The bigger difference is storage, because right now, Port87 is fully NVMes. I’m working on implementing RAID arrays so I can lower the cost of storage.

Fun fact: adding more domains to your account does not cost me (or Proton) any more money. That’s why I priced it at one payment for unlimited domains. I’m not really sure why Proton limits you to 3.