@Ismas the architecture (target) in menuconfig is called "Ralink RT288x/RT3xxx", under which you find a subtarget "MT7688 based boards" and finally the Omega2 profiles.
Before starting to dig through Linux sources for these SoCs I hadn't realized how difficult it is to relate chip names to their architectures and drivers. There's little logic in it, but a lot of history.
How would one be able to guess the MediaTek 7688 goes under the "Ralink" architecture? Of course, once you know that Ralink was once a company that made MIPS based SoCs, and was aquired by MediaTek in 2011, it makes sense.
Still, support for the MT7688 can go by any names with "ralink", "rt", "mt76" "7621" and probably quite a few others. Comments in drivers often refer to subsystems that probably once were separate chips and thus had a completely different number. And all this being in the mostly proprietary SoC world (few proper datasheets) makes it hard to figure out what belongs where. So it took a while for a beginner like me to even start connecting dots...