I did that with my first generator. That was 20ish years ago so the Generac and similar units were not common back then. I had a tri-fuel generator tied to a sub panel that powered a bit over 1/2 the house.You can get a smaller one with a subpanel that will run just the stuff on that panel.
When power is out, in an emergency situation, you can live without quite a few of your circuits. We powered the microwave but not the double oven, etc. Pretty easy to make some of the choices.