Automatic document creation?

Hi Joel, you're kind of describing a text book use-case for Syntex. if you are already an M365 shop and have (or willing to get) a Syntex license, then yes, I think Syntex is a good fit for what you describe. Your product content could be in Sharepoint list(s) then assemble product guide docs either as required or en-masse. Your existing manually created docs may need to be deconstructed from the docs into the list columns but Syntex can assist with that process as scale as well. As for automated approval workflow, Power Automate should do that ok and it also talks to Syntex.
I have a prototype of all of the above if you really did want to see a demo. Let me know if you want to set something up.