The conti kit is called the 'comfort' kit and injects a liquid sealant into the tyre via the inflation valve & inflates the tyre with the integrated 12v compressor.
Generally pretty good unless you have a big hole (or torn sidewall).
It is very common now to have cars equipped with these systems in place of a spare tyre but I have to admit even as a tyre engineer by profession I paid an extra €40 when I got my last car to have a real spare wheel (even if it is mini-spare) as well as the repair kit.
I don't think the tyre-weld cans inflate the tyre sufficiently from memory, and the speed you can continue driving is drastically reduced (40mph or so I think)…
The challenge is identifying you have a flat tyre before you have damaged it beyond repair. Harder than you might imagine especially if it is on the rear axle….
When pressure monitoring becomes a legal requirement that aspect will disappear.