I guess I should add some potentially helpful tips for anyone that comes across this. We were able to get an extra 2+ years out of our 2012 Camry Hybrid 12v battery by spending ~$30 on this battery charger from Amazon (it's currently $25.99 today on Aug 21, 2022 so even cheaper than I paid back in May 2020).

We were living up in the Northeast in 2020 and our first winter up there killed the battery (we hadn't driven the car in awhile with all the snow). I used my multimeter to check the voltage and it was under 11 volts. Like the battery should've been unrevivable according to everything I read online.

I used that cheap battery charger's "repair" function, which does a slow pulse charge, for like 24+ hours and it brought the battery back to life. I periodically checked the voltage of the battery with the multimeter and it stayed above the healthy threshold (12.5+ volts I think?). And then it wasn't until today, on a regular unremarkable August day in the midwest, that the car just wouldn't start and the battery is now reading ~11.2 volts.

I have it hooked up to that battery charger again so we'll see if I can bring it back from the dead once more just for the sake of moving it out of the way in our driveway.

Anyway, hope this can help someone else get a few extra days, weeks, or years out of their hybrid 12v!