Just focus it until it’s as clear as it can be—it’s the best you can do.

No. It’s not like looking through binoculars, where the lens of your eye becomes effectively the last in a series of lenses, each taking the output from the previous one and refracting the rays slightly. In the binocular scenario, the lenses “upstream” from your eye need to be adjusted to compensate for the refractive anomalies of your eye, so if I look through binoculars adjusted to your eye, they will be out of focus for me.

But in your camera, the light from the lens is reflected up onto a fresnel screen in the viewfinder. You’re looking at that screen, which is roughly analogous to looking at a movie screen. At the theater, the projector doesn’t need to be adjusted for people of different eyesight. What’s clear for me at the theater is clear for everybody.

No. You’re eyeballs’ optics do not affect the cameras optics. The distance from the lens to the sensor does not change. If you are having a hard time you can buy a corrective lens for the camera eyepiece. Undersize rather than oversizing. For example, if you need +2.0 diopters to read now, try a +1.0 or +1.5 diopter . That will reduce your eye’s focus acquisition time when you look between the camera and the subject.

As @LuckyGuy writes, a diopter can adjust the view as if you are wearing glasses.

The Canon T5 has a built-in dioptric adjustment. It’s the little +/- wheel next to the eyepiece. I believe it works just like the T3 and here’s a link.

Adjusting the Viewfinder Focus on Your Canon EOS Rebel T3/1100D

Reading glasses are for viewing things up close and I am assuming your ability to see in the distance is decent. If so you should have no problem getting your shots in focus. I am pretty blind without readers and can take clear picture with manual focus on my Nikon no problem. Post a couple pics when you get a chance. Here is one of mine

This and this are from today (it’s overcast and very dark, with a steady sleet falling. I have literally hundreds of birds in my back yard – we’re the only house in the entire development that puts out feeders).

@syz You are golden as those are awesome shots especially if you used manual focus as you nailed them and having low light conditions!

@syz The backgrounds are out of focus, you must be nearsighted. ~!

There’s a definite learning curve, but I’m enjoying practicing

You’re not simply practicing anymore. Wow!