This is a REALLY long post, so I apologize ahead of you reading it (or just starting to read it)....
Background
The lack of guidance from Chevrolet on this issue has made people hesitant to change the tires/wheels themselves. I understand that position, as you have to accept liability for what you do yourself if you damage something or injure yourself. But to share my experiences, I'm 63 years old and have no real difficulty changing the 21" wheels on the Blazer EV. By the way, changing the tires on any car can be dangerous/deadly, especially if you don't know what you are doing or pick the wrong place to try to change the tire. For me, I did grow up on a farm and was accustomed to maintenance on trucks/tractors as well as whatever car we were driving, so I might be a little out of the norm there in my comfort level. I do think it is important to select the right jacks and pinchweld adapters to use, but that has been pretty well discussed in this forum thread. I also use wheel chocks whenever I change a tire. It is a deal breaker to me not to travel with a spare and to be required that the dealer/shop change wheels/tires for me.
Jacks
BTW, I like the scissor jacks from the Traverse/Enclave/Acadia for swapping wheels on the Blazer EV. They are taller jacks and have a good flat surface to meet the round aluminum pinchweld adapters I use. They have a pretty good base for support with the ground, but carrying a good base support in case you have to work on softer ground might be a good idea (hopefully you can pull off onto an asphalt or concrete parking area and this isn't an issue - remember one of the biggest safety points in changing a tire is choosing where to do it - a nice level hard surface away from traffic is certainly desirable). I went ahead and bought 4 of of these jacks on Ebay at just under $30 each. I'll keep two in the Blazer EV with a third low profile scissor jack in case the Traverse jack turns out to be too tall after a complete flat. They only weigh about 8 lbs each, so not enough weight to be concerned with carrying, and there is plenty of storage under the floor in the back. The other two, I'll keep in the garage so that I don't have to dig the two in the car out of the storage area every time I want to rotate tires. I plan to just rotate tires front to back. I don't think that the criss-cross rotation adds much to the life of tires and just isn't worth the effort. I'll watch the wear to see if I change my mind on the worth of the criss-cross effort.
Tires
Also, I might change my mind, but right now I plan to run Vietnamese made Blackhawk Agility SUV 275/45/21 tires as my replacement tires. I've bought 6 of these so far, 2 of which are on the rear of the Blazer EV and 4 stacked in my garage. They are really good tires for the money (about $143 each delivered including tax from Ebay). I believe that they are also available at Wal-Mart at not much more than that. Reviews are really good, especially for a tire at this price range, and I can't tell any difference in the ride after putting two on the rear of the car. If anything, it is smoother and quieter. I'm not really impressed with the self-sealing Bridgestones that come on the car. It's a sticky mess inside the tire after removal, and the self sealant didn't work the first time I needed it to. I could patch the tire that went flat (at 19k miles it isn't showing more than 1/3 wear), but the sticky goo inside the tire looks like it will be a pain to manage to clear away for a patch. I did order some mushroom patches, so I might give it a go, but with the inexpensive tire replacement option I'm looking at, I'm not sure it is worth the effort.
Torque Wrench
Also, the recommended wheel lug torque for the Blazer EV/Equinox EV is 140 lbs. I also keep a torque wrench in the storage area for this. 140 lbs is a good bit or torque, so you might want to make sure you are prepared for that.
Spare Wheels
Also, BTW, I have purchased 5 additional OEM wheels on Ebay for about $275 each (one is the spare I carry all the time) for the Blazer EV. It is too easy to just drop off wheels and tires at a tire shop and not leave the car when changing tires, then drop by and pick them up when ready. With the EL50448 electronic electronic TPMS reset tool (available on Ebay for less than $10), it takes less than 5 minutes to reset the TPMS to work with the new wheels.
Feel free to pick at me, especially for buying extra wheels and for the cheap Vietnamese tires (I wish they were made in the USA, but for several hundred dollars of savings, I can get over it - I've put 20k miles on this vehicle in 12 months and expect to pretty much keep that pace, so cheap tires are helpful to the long term economics). Way too long a post, so feel free to pick at me for that as well.
As a final note, don't mess with this if you have never changed tires or just don't feel comfortable doing so. Just because I feel comfortable doing it and choose to do so doesn't mean it is the best path for anyone else or even for myself for that matter. You should weigh all your options and decide what is best for you. And if you do decide to carry a spare, you must secure it well so that it doesn't likely become a projectile in a crash, and remember that securing a full-size spare is much more difficult than securing a lighter temporary spare. I've got mine strapped down pretty well, but in a severe wreck I'm not positive it wouldn't break the straps or break the tiedown points. I do know I take that risk, but I try to minimize it as best I can and weigh it against the risk of being stranded somewhere I don't want to be with a flat.