Here's a good option for an eSIM from KeepGo for minimal/backup use in North America - the KeepGo Sagittarius, can buy 100Mb for $3 (or 1 Gb for $8) and it's valid for a year (they have a coupon that adds 2Gb for free right now), roams on AT&T and T-Mobile. Refill at least $3 once a year keeps this valid.

They have a bunch of other versions depending on international destinations, for those inclined - should probably post/discuss that in the eSIM thread.