I’ve been using Chrome Remote Desktop with my parents. Takes a bit to install but once they have it, they just click on the Remote Desktop in Chrome, give you the code, accept the connection and you are in. For iOS devices - a FaceTime call you can now share screen (I think its only iOS 15) and its much easier to tell them where to click to troubleshoot. Both solutions have been working really well for me recently.

Chrome Remote Desktop is what I'd recommend too. If they already have Chrome it should automatically install the rest (with a confirmation) when they try to share the screen.