Hi @ralex,
As you said, Power Pages is an app to create a web page.
MS Forms and Google Forms is a kind of web page as well.
I believe this might be a good referance guide for you to add a form to your web page.
You can control to publish it to the public or keep it a private.
Tutorial: Add a form to your page | Microsoft Learn
In order to make a good form to get the info, you need to design a table with Dataverse.
When you design the table, you will see all the options including a file upload feature.
(9) Create Tables in Dataverse – Part 1 - YouTube
These would help you to solve the problem.
I also created a demo web site (built by Power Pages) which has an event application form.
The form asks the name, phone number and email of the applicant.
As sood as the applicant submits the application via the web form, the answer works as a trigger to automate a flow to create a QR code and send it to the applicant (automated by Power Automate).
Power Apps helped me to create a QR code scanner to read the infomation in the QR code.
I recorded how to create a web form with Power Pages and automate with Power Automate and build a QR scanner with Power Apps.
Unfortuantely, I recorded those in Korean.
If you want to watch how to do those, you may visit a play list of these.
(9) Power Pages & Power Apps: GPPB2023 행사신청 QR코드 스캐너 - YouTube
Actually, there's an option upload files in MS Forms.
However, it is only active for the internal users, as you might know.