My opinion: you can rely on earnings from donations only if you plan (and will) expand and supplement the game content over a long period of time. Otherwise (if your game is completely finished and will not be updated anymore) the best approach is a paid full version + a free demo version.
Interesting suggestion. Something to really think about.
For me, based on my current experiences, I think if what I’m offering is something I plan to charge $1-$1.50 for, that I’ll probably generally try the $0+Donate model and see how it goes. Worst case scenario is no one donates, best case scenario is that people will appreciate a free product and that some people will donate and that when they do, they might feel more prone to make larger donations than $1-$1.50.
But… if I’m considering a $2+ price tag, I think I’d put an actual price tag on it.
My suggestions might of course be different if we’re talking a big studio or one that spent substantial time or money on their release.
Know your audience.
Filter for tags describing your games and see what pricing model similar games used. Scroll down a bit for less famous games that still sell. Unfortunately you do not know at first sight how much promotion those games did. Maybe they have Steam fame or other things. I mean, there is currently a prototype on page 1. But on their devlog they talk about having actual funding, not only the trickle of donatinos on Itch.