Supporting a technically naive parent on macOS & iOS?

I remotely support my technically naive and Alzheimer's-suffering mother, who uses a MacBook Pro and an iPhone. I've been using **Third Party Product** to support the Mac, but their pricing is getting out of hand and they've become a little unreliable recently, so I'm looking for alternatives. TeamViewer seems like it may be the best choice, but I have a couple of questions.

For remote access to her MacBook Pro, can I configure it for unattended access? And will that configuration be stable? I do a lot of my support while she is at dinner or otherwise away from her laptop because otherwise she gets confused and I get annoyed at all the questions. And if the ID and/or password can change (as was suggested by one video I saw), she's not up to finding them and giving them to me. I don't mind on-screen notification that a remote session is in progress, but I need a way to connect that doesn't require any action on her part once everything is initially set up.

I currently have no solution for supporting her iPhone, but think TeamViewer could really be helpful there. I'm less worried about unattended access, since I wouldn't access it without being sure she wasn't using it for anything, but the ability to have a pre-configured and stable connection is essential so that no action on her part beyond accepting the remote connection is ever necessary. Is this possible with TeamViewer?

Thanks in advance for any answers or pointers to documentation that addresses these questions, and apologies for beeing such a n00b.