Can specific wired or wireless device(s) based on their MAC addresses connect to internet using the VPN on ASUS RT-AX92U AIMesh system. All other devices should connect through normal internet.
Not with currently available stock Asuswrt firmware. What you have available is all or none. Eventual 388 firmware update will give you the option you need via VPN Fusion. When/if 388 is coming to AX92U is unknown. This router is mid 2018 model and had no firmware update for about a year.