Interesting remark.
But normally with extender in 802.11 wifi connection, all devices behind the extender use the same MAC address of the extender for the wifi connection (One MAC address & multiple IP addresses.) Exceptions on that are "WDS, bridge mode, mesh". But these last 3 are not always working between different brands.
Other solution is to make a tunnel between the 2 wifi devices.
It then has to be a Layer2 tunnel (L2TP, Zerotier, VXLAN, PPTP-BCP, EOIP,MPLS/VPLS...). Zerotier is a very nice one, and will eliminate all intermediate routers of Zerotier-world-network when it can. And here it will be a direct connection.