Here is a somewhat weird comparison between a Leica Q2 with built in 28mm lens and the Canon EOS R5 with a rather old EF 28mm f/1.8 lens. The lens on the Leica is newer, more expensive and a bit faster.
More Canon EOS R5 review stuff is listed here, for EOS R6 review stuff see here. The EOS R5 is highly regarded as a stills camera. In particular, the EOS R5 autofocus system seems to be huge leap forwards. User manual are available for download for the EOS R5 and the EOS R6.
Canon EOS R5: