A Wi-Fi repeater is essentially the same thing as ... Small routers, like the TP-Link TL-WR1502X when set to "client mode," can act as Wi-Fi bridges. Of course, given that pretty much everything ...

While it doesn’t appear that [bethiboothi] is using it currently, the esp_wifi_repeater firmware does have an automatic mesh mode which seems like it would be a fantastic fit for this design.