This is full dump RA75 include Openwrt from Flash chip.
https://drive.google.com/file/d/1O4tOajugmbNXa-O6LtYIqjbPwSQpxNtC/view?usp=sharing
You try to restore !, I'm not sure it works because I tried to restore the full dump include Openwrt to another RA75, but it doesn't work, there is a boot loop.