A Shield TV is probably overkill for you and the recommendations of a pi would do just fine, but if it’s in budget I say go for the Shield TV. Mine is nearly 8 years old and I haven’t had a single issue, streams 4k HDR, and runs so much better than any of the crap that comes with even the newest of TVs.
Do you have a “vices” budget? Maybe that’s one approach. You both get $100 or whatever and she blows hers on mobile games, while you’re cutting back and have money for other things.