To say I'm un-impressed with the speed at which Optus approve updates for my device is an understatement - Yesterday I received the November security update whereas other AUS networks and carrier free phones in AUS are now onEMUI 10. My very old carrier free Samsung S7 even has the december security update.
I doubt that Optus will ever meet my expectations so I'm wondering if there is a possibility of releasing my phone to allow it to receive updates as if it was carrier free. I'd happily sign any sort of disclaimer stating that I only have the manufacturer's warranty to rely on.
This would then put me in the same boat as my previous phone that I bought carrier free, so I don't feel I'd lose any support.
It's the warranty that gets you. You can flash the stock version of the software to your handset but I'm not clear on if that means your warranty is void to. If it doesn't void your warranty, it would do exactly what you're asking for