Going by iQOO track record do not expect any development or custom roms in future. It would be good for 2 years then you'll have update to new phone. Do not expect any development. Like LOS, Even simple bootloader unlock and root will not be possible.
This is actually true for almost all Android phones these days. I want able to use my S9+ Street 2 years because it's battery decayed pretty fast. My wife's phone's displayed died. She had the S9 and we bought both phones together.
Updated and custom ROMs aren't that great these days because of plethora of phones and great devs of this forum also can't keep up with whether to fix issues with current build or to push next update build.
I used to own an HTC Wildfire S and its devs were pretty mind blowing. It used to have great ROMs which were much faster than stock. But these days stock ROMs are also good enough if you disable some bloatware and irrelevant system apps.
I have disabled some system apps using adb and am not facing any kind of adware notifications and the phone is smooth as ever.
I never even tried to root my S9+ also since I never found any good reason to lose Knox and DRM capabilities just for a little bit faster but still bugged ROM since I had the Exynos version.
With stock I prefer the peace of mind.
I've shared all my thoughts with you on this, now choice is yours.
Quite right. And will there be something significant better then screen 120hz, 12gb ufs 3.1, incredible fast charging, 120 watt 18 minutes fully charged, exceptional good battery management, at least 36hrs with full use of phones possibilities. Processor SD 888, good for the next 4 years I think.