I need to understand the issue better. You say you have transitioned to mirrorless. Did you have this same problem with your DSLR or other cameras?
I wear sunglasses and contacts and sometimes trifocals, and sometimes no corrective lenses at all. The Canon cameras have a diopter adjustment for the viewfinder and it takes only a couple of seconds to set it up. I adjust it as needed on the fly for the condition I am shooting in e.g. corrective lenses or not before I begin shooting. If you wear sunglasses while shooting you may need to brighten the viewfinder and this can be done in the menus. Sunglasses will play havoc with your perception of exposure simulation in the EVF so it becomes necessary to keep an eye on the EVF exposure meter to correctly judge the exposure. This is less important without sunglasses.
Often when wearing sunglasses to spot shots I will push them up on my head or have a neck strap for the glasses so I can let them slide off and hang while I take the shot. I set the diopter for the lens correction I may be wearing such as contacts or for no lens correction as necessary prior to shooting.
If you wear bifocals or trifocals you will look through the viewfinder and adjust the diopter to achieve the sharpest view of the EVF. I use the Exposure scale and text as a guide to determining the correct adjustment. Once that is made you should be all set.