Make a Facebook Page on your phone
You do not need a computer for this. Making a Page is four taps in the Facebook app, and it takes about three minutes.
A Page is free. It is separate from your personal profile: your friends, your photos and your own posts are untouched, and nobody is told the Page is yours unless you tell them.
Facebook does not let any app post to a personal profile — only to a Page. That is their rule rather than ours, and it applies to every tool of this kind.
Doing this on your own phone has one quiet advantage: the Page is yours from the start, so the permissions problem that catches most people never comes up at all.