fastboot -w has been around since forever or so, and it does format data. That will absolutely erase your user data, as if you'd done a factory reset and wiped everything on the internal sdcard.Mauronofrio: First of all congrats and many thanks for the awesome job you're doing.
I'm not too clear on what you mean by “fastboot -w” (sans quotes). You said this is to format data. Will it delete anything? Also, should you issue this command before or after applying the batch file?
I imagine you're a busy man, but whenever you get around to it please put out a zip with all those img files for "OnePlus8Oxygen_15.O.30_OTA_0300_all_2010031624_c5e68b42b3325". This just came out today (Oct 24) and, as you know, it cannot be flashed.
Before this Project Treble garbage if we bricked the phone we could easily flash the OxygenOS Rom. Sadly that's not possible any more. Do you believe this is a viable alternative in case disaster strikes? I still have a working copy of an old version just in case, hopefully it'll still be flashable.
Back up your important stuff