I have used contact lenses in the past (though I didn't really like them for everyday use so I just wear glasses now) and/or a camera an optical viewfinder with diopter adjustment, which is sufficient for my long sightedness, but I'm lucky in that the eye I tend to use on the viewfinder is the "better" one as well.

You used to be able to get aftermarket eye pieces to attach the the camera as well which either put more distance between the back of the camera and your head in order to make room for glasses, or (more rarely) had or could accept additional correction lenses.

I'm not sure if those are a thing still for the newest cameras though - the move towards EVFs make it even more of a niche item.

I think many viewfinders have a mechanism that can adjust the magnification of the viewfinder regardless of whether it’s electronic or not because it’s an optical adjustment. Old film SLRs even have this.