I've got the Nissin MF-18 that worked perfectly fine with my DSLR's, but currently won't work on my Z50 and Z5, Nissin have done an firmware update for the Z50, but are considering one for the Z5 and the rest of the Z cameras, hopefully it won't be too long, I'm not sure if the Sigma ring flash has the same problems.
I've currently got the Nissin MF-18, which worked flawlessly on my Nikon DSLR'S, but doesn't work with my Z50 or Z5, Nissin have released a firmware update for the Z50, but not one for the Z5, Nissin are considering updating it for the Z5 and the rest of the Z cameras, I was going to sell mine, but I'm hanging on to get the firmware updated when the UK distributor gets back to doing non warranty work.
I'm not sure if the Sigma ring flash is the same.