Battery dead after returning from 8 day trip; how best to proceed?

congrats! buy a volt meter and keep an eye on it so you don't get stranded again.

 

I’m not. It’s a great way for the dealership to make money, like all the other unnecessary and recommended repairs.

 

Most people won’t check oil level, checking voltage is even more of a drag, or sand pounder

 

I'm happy it's working for you, and for no cost!
If you plan to be leaving on frequent trips, you could but a solar charger and attach it to the battery
then lay the solar panel on the dash. It will keep the battery charged up.
And/or get one of the small battery jumpers for about $50. But also, get an AGM battery charger.