This section in the WiiM Mini manual (and a similar section in the Pro manual) would suggest so (but not using airplay):
”9 . CONNECTING VIA AUX IN
WiiM Mini can be used as wireless WiFi transmitter that can stream the analog audio input from CD player, recorder or computer to another (or multiple) WiiM Mini connected device.
To set up the WiiM Mini with the Aux input:
1. Plug the 3.5mm cable into the Aux in port on the back of the WiiM Mini.
2. Plug the other end of the cable into the record player.
3. In the WiiM Home app, Go to Browse > Select source on device > Aux in, select the Aux in for audio distribution.
4. Create a multiroom music group with your WiiM Mini. On WiiM Home app, Go to Devices, select the WiiM Mini connected with your Aux-in device. Tap the group button (with + sign in a box) in the top right corner of the device box. Select the WiiM Mini you wish to connect with.
Once completed, the music playing from the device plugged into the WiiM Mini will play to your multiroom music group.“
I take it then that you would use a physical aux in connection from your receiver into the first Mini and a similar physical aux out connection from the destination Wiim into your speaker, with the Wiim to Wiim connection being supplied over wifi using the Linkplay multi room protocol (not airplay).
Edit: for clarity, if the speaker doesn’t have a physical aux in socket, then you’re out of luck. The target mini couldn’t use airplay to connect to it in the same way that the Pro couldn’t - it’s not an airplay transmitter either.
