If you're not concerned about spam, you can just add your email address to your Nostr profile.
To make a web form, it's a bit involved. You would need a web host, like
https://www.infinityfree.com
From there, you could install WordPress, add a plug-in for a form and captcha, and have the results sent to your Protonmail.
After doing a quick search, it appears there are some free tools that you can use with just a static HTML page (no WordPress). Those tools are:
https://aidaform.com/templates/contact-form-with-captcha.…
and
http://www.snaphost.com/captcha/ReadyForms/ContactUsForm.…
After I do some job searches today, I'll look into this further in case you need help.
Another simple option is to create an email address with
https://tuta.com and let the spam fly, along with order requests. That way your Proton account doesn't get flooded. It might be a mess to sort through, and Tuta makes you wait for approval before the account can send or receive, but it's simple.