Universal repeater mode with WWAN failover

I like to create a local WiFi network for a bunch of devices, that connects to the inteet via another Wifi AP or UMTS WWAN, if the WiFi connection fails.

As there are many devices in the local WiFi network, but the environment network may change (ETH cable, some WiFi or none of them), the local network would provide a constant configuration for my local devices.

There are routers that provide WWAN failover, but they only provide AP mode (the Inteet is connected by Etheet then) or client mode (The inteet is connected by WiFi, but there is no local WiFi AP then).

There are routers with "Universal Repeater Mode", which allow to create an local AP while still being client in some other WiFi.

So it is possible to have AP WiFi, client WiFi and WWAN failover if the client WiFi fails on the same device? Or are there reasons that make this impossible? What features I would have to look for to find such a device?

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