Yep ... previous consumer electronics company I worked for did the same! You didn't want to open the flood gates to millions of devices due to bandwidth and more importantly if there was a issue caused by the new FW push. We would enable a couple of hundred, take the pulse of customer care, and roll out slowly day by day over the course of a few weeks. If an issue was found, updates would be turned off, and the issue triaged. I'm sure Lucid, Rivian, Tesla do the same thing for the same reason.
Also, even Apple also does rolling deployments, just on a smaller scale because they have an active beta program. Even when they do release to GA, you’ll often see “download queued” so as not to overwhelm their servers.
Full fleet-wide simultaneous releases are rarely a good idea.