I think this will not go down well here on HackerNews because I'm going to suggest sticking up to Apple. Here is my experience. I tried with cheaper phones that we can just replace when they lose, drop it, or many other reasons.

Get them on iPhones, Macs, Apple TV, and iPads. They can be used ones or hand-me-downs, but that ecosystem works for them. Here is a setup for the in-laws.

An Apple TV drives as the "Apple Home" Setup while an iPad (the backup) is mounted near the TV. That room/area is the "talking to the kids area" where they just know how to respond or start a video call. The only other button they learned was to switch between their favorite local cable provider and the Apple TV. It did take a lot of repeated practice from "I can see on the iPad but not TV" to "seeing and talking on the big TV".

iPhones/Macs (instead of selling yours, give them your old one) are the easiest to set up and maintain. The contacts sync, and they have stopped complaining about getting back their phone contacts. The father-in-law once hand-wrote about a 5-paged A4 with about 200+ odd numbers and came to me to sync to the new phone. They are not losing their photos anymore and can spend hours browsing photos of their gigantic family members.

Tip: Set up your Apple TV screensaver with a specific Album and keep sharing photos there. Now, watch the grandparents, grand-everyone just sit in front of the screensaver and spend hours talking, laughing, arguing, crying, and sleeping off.