99.9% of regular people think website = .com. All of the other TLDs are functionally equivalent to ThingApp.com (not Thing.app) or ThingIo.com (not Thing.io.)
Choose whichever name works with a .com domain.
Choose whichever name works with a .com domain.
your entire service's web presence can live on an instagram account, it does not matter
so although I am a proponent of using prefixes and suffixes, I'm also a proponent of obscure tld's or just not even bothering, and just hosting on github pages, you can even give direct links to cloudfront if you want
focus on things that do matter which is revenue, this debate doesn't even matter