SMS is fine for 2FA, as long as you can’t use it for anything else, like a password reset.
Once the SMS is used for account recovery, it’s now 1FA with a terrible security hole.
If you have complex, single use passwords, and have SMS 2FA, then it’s pretty ok. Not the best security, but at least better than a most.
Obviously offline time based passkeys are better for the 2FA, but typically the real problem is how to get into an account if you’ve lost one part of your login.
I’ve been running a pair of cyberpower systems for over a decade. I had to replace the battery in each of them once, but they’ve been working great.
I assume newer ones use some sort of Li-Ion battery tech, but mine are just plain old Lead Acid.