In googles settings you can turn off watch history and nuke whats there, which should affect recommendations to a degree. I recommend you export her youtube subscriptions to people she likes (that arent qanon), set up an account on an invidious instance, and import those subs. This has the benefit of no ads and no tracking/algorithm making. The recommendations can be turned off too I think. Freetube for desktop and newpipe for andrioid are great 3rd party youtube scrapers. The youtube subs can also be imported to a RSS feed client.