DeDRM extracts the keys from Adobe Digital Editions. So you need to have Digital Editions installed (use a Windows VM if you are another OS) and added the E-Book to the library.

Yes: https://github.com/beacondb/beacondb-unifiednlp

It might be worth setting up a seperate Chromium extension store independent from Google

It does (they of course use their Azure Blob storage under the hood). Forgejo however does not (even though it supports it for releases and packages and Golang has this in their standard library).

I’ll keep the idea in mind.

Technically unlimited, but you obviously need to have enough storage to cache the zip files (and RAM to cache the file index). My server is very small, so I needed to set the limit low.

No, that temperature would damage your screen. The professional hot plates for phone repair are typically set to 85-90°C. With a heat gun you may need to set a higher temperature since you are only heating up part of the phone and it cools down again during the process. My printer (Prusa MK3) with PCB heater can go up to 120°C, so it looks perfect for the job.