Andorra is not in the European Union. That one fact changes everything about your phone bill. The "roam like home" deals that work across France and Spain usually stop the moment you cross into Andorra. A single megabyte on your home plan can cost a small fortune here.
There is one mobile network in the country. It is run by Andorra Telecom and the brand you will see is Mobiland. Every eSIM you buy connects to this same network, so the question is not which network you get. The question is how much you pay for the data you use. That is where a prepaid eSIM saves you real money.