Ouch! Good luck with your surgery, and do remember that every time you DON'T stand up, you probably bring your healing one day sooner.
That said, maybe there are some things that can be done from a chair ... IF you have really good access to some of your beds. Hoeing weeds or cultivating between rows, for example. Some tilling can be done with a long-handled shovel, but it is awkward and inefficient.
If you have a sharpshooter spade (trenching spade, ideally with a longish handle), you can scrape a planting trench within a few feet of the edge of a bed, preferably parallel to the edge. Then place a seedling on the blade of the spade, and slide it into the trench, leaning against one wall. Place a few more seedlings. Then skoosh the soil back into the trench so as to make the seedlings stand upright, then level things off and firm the soil down. Then move the chair.
But you have to be able to reach the tray of seedlings.
I think the biggest problem is that wheelchairs and gravel, mulch or soft soil do NOT combine well. I'm sure you're going to put your EBs on a flat hard surface that you can get your chair to.
IF you can firm up the approaches to one or two beds, that might bring them within reach. For one season it won't be worthwhile to lay down a sidewalk, but maybe someone could lay down two rows of concrete paving stones (18" x 9" x 3/4") as wide apart as your wheels. (Hopefully your yard is very flat!)
Next year those paving stones could become the walls for new raised beds.
Maybe if the soil is very hard, the grass could be mowed very short, and you could roll right over the grass. If not, it is often easier to drag a wheelchair backwards over a bad surface, than it is to push it or roll it. If one person pulls and steers, while you push the wheels (backwards), you might get over a rough or soft surface and even up a bit of slope.
Once you get there, you'll be really motivated to stay there until you've used up all your upper-body strength, making the return trip harder, unless the return is downhill. But it might cure some of the garden-deprivation-withdrawal.
Good luck with the surgery, but they probably do it every day and know how to do it perfectly.
Good luck dealing with cabin fever! That's more problematic, but it is within your control. Tell yourself "it's only a few months" until you're tired of hearing that and "a few months" sound like "20 years". THEN take it one day at a time. You can almost hold your breath for one day!
Maybe start a lot of very difficult perennial seedlings in trays, indoors.
Maybe spend a lot of time reading seed catalogs or on ATP.
