Collecting Signatures on an Excel Sheet

I've got 400 employees who all need to be able to edit and sign off on their own excel sheet. Then, their supervisor needs to sign off on that same sheet. Also, each employee is not allowed to see anyone else's excel sheet. Supervisor's can see all of them. It's fine if at the end of the process it becomes a pdf or any other format. But, I need it to be editable for the employees at the start.

What would the best process for getting signatures on these excel sheets? I'm thinking of having power automate generate all the individual sheets and emailing them out to each employee, but I'm not sure where to go from there.