The dumper is just a corner case workaround
The easiest way would be to fastboot boot the stock twrp on the stock ROM, flash the AOSP zip, maybe the dual sim patcher and what you need
Then in fastboot flash the OEM binary
And then you could boot the system or install the sodp twrp.
Nvm, it worked flawlessly at the end.
It was me just being impatient at fastboot commands thinking that bootloader just got stuck.
Also i managed to boot to SODP TWRP and did the mistake of wiping system.
So went back to flash stock again (twice today).
What's the difference between the codenames at your TWRPs in SODP folder at Android FIle Host (like one dated at 11 of June with SODP codename on it, and the other dated at 13 of June without it, as they're both under a SODP folder; again feel to forgive my dumbness if that's a silly/obvious question to you)?
P.D.: Yours is a smart solution. It's just me being dumb or something (it's not only today when it happens to me sadly, lol), or liking to make even harder my life (in this case was the first, rofl).