Looking for an elderly friendly smart TV or streaming device

I am looking for a TV solution for my 90 year old grandmother.  She has cut the cord and cancelled her cable TV service, content to watching youtube on her desktop PC.
She does miss sitting back and enjoying TV in her living room though, so my plan is to equip her with a television and wireless USB keyboard to navigate the TV with.
However, she definitely will not be able to navigate a smart TV/streaming stick menu to pick out the Youtube app.

So I am looking for either:

A TV that will default to a selected app, like the Youtube app, when powered on

OR

A TV that can default to a given HDMI input when powered on and pair it with a streaming device/stick that will default to a given app AND can take a USB keyboard for input

Any recommendations or some other solution I hadn't considered would be greatly appreciated