3 years are insufficient for high-end smartphones, 12 Giga and more will be able to support 4 major versions and more.
Intelligently used battery by-pass doubles or triples its lifespan.
The equipment in 2008 to 2015 did not allow to follow the evolution of Android over 2 years, the same in 2016-2019.
The Android 10, 11, 12 evolution is stable in memory and cpu usage, the APIs evolve little.
It is foreseeable that a Rog 3 will still be perfectly usable in 2023 or a Rog 5 in 2024-2025 and that the hardware fully supports Android 12, 13 and 14 if of course the battery is good, which should be the case if the bypass is used whenever possible.