The foam isn't something added. They are a feature built in to the OEM tires by the tire company, not a Tesla add-on, and aren't meant to be "transferred". I've had a Discount Tires refuse to patch a nail in one of mine because they were told they couldn't because of that foam. I wound up doing the plug myself with a kit and the tire did just fine until it was time to replace all of them. Have gone on to do the same with my wife's on two different tires (too much construction debris on roads these days!) Since then, I have put different tires (Pirelli Scorpions) on my wife's car that don't have the foam. That wasn't the reason for picking the tire, they just had better life and all-season tread. They are a little noisier, but only if you're thinking about it.
Regarding the original topic, I wasn't crazy about not having a spare when I bought my first Tesla, but I thought about it and had to agree that in 38 years of driving, I've had to change a tire maybe twice, and even then it wouldn't have killed me to wait for roadside assistance. Spares made more sense back when tires failed more often, or before TPMS alerted you early on to a leak, and more to the point they made sense before everyone had a cell phone to call for help. Kneeling on the ground with a lug wrench next to a road with distracted drivers is not to be taken lightly. Sure there's some pride in saying you can do it (and I've taught both my daughters how to change a tire), but there are safer alternatives these days. If you know you are one of those people who travel to an edge case location (no cell reception, no traffic, no roadside service anywhere), then by all means it makes sense to invest in one of the aftermarket solutions. It's just not that common.