When I imaged using my Canon camera I did try using a right angled finder but it proved unsatisfactory for me. I progressed to using ASIAIR which supports some Canon and Nikon cameras.
https://i.zwoastro.com/zwo-website/manuals/ZWO_ASIAIR_PRO_User_Manual.pdf
The disadvantage for a DSLR user of the ASIAIR solution is that they need a 12v power supply.
I think NINA (Windows only?) also supports any DSLR that has an ASCOM driver available.