Do you mind elaborating on what you did to get your QHY294M work with INDI nightlies installed via Astropi3 on your RPI4?
I have Astropi3 running on my RPI4 with INDI nightlies on UBUNTU-mate 20.04.1.
INDI doesn't recognize my camera. lusb lists it as a USB2.0 Hub:
esktop:~/Desktop$ sudo lsusb
...
Bus 001 Device 025: ID 1618:c296 USB2.0 Hub
...
5-qhyccd.rules does list this camera and the firmware image is located at:
~/Desktop$ ls /lib/firmware/qhy/QHY294PRO.img
/lib/firmware/qhy/QHY294PRO.img