Onedrive Doc, Multiple choice on Approvers, special instructions with doc

Folks, 

I am a novice with Flow, but went through the tutorials, and this community looking for a solution. Hoping you can point me in the right direction.

I want to have users add a document to OneDrive, and select which Approvers need to edit/approve the doc. Perhaps I could have them either add Approvers emails or select from a list/form. I also want to allow the requester to provide special instructions. I tried the trigger start with a Microsoft Form but it will not allow me to attach a document. (one option is to upload it to OneDrive and have them insert a link in the Form I guess).

I built the flow that starts with a doc upload to Onedrive, but cannot figure out how in the flow to drive the requester to a form thereafter to select approvers and add special instructions. Also, since I can have many requesters, and each requester can have multiple docs in the approval process at once.

Our firm does not use SharePoint  for an intranet (yeah I know OneDrive is essentially built on it).

The "Request sign-off" feature in OneDrive under the "Flow" menu item is missing, but the Microsoft literature says it was available Feb'19.

Question: Can I construct a flow for document approval, that allows requesters to select approvers, and provide special instructions?