Keep is an app my wife and i use quite a bit and would love to find an alternative on iOS (if there is also an Android app that would be a huge plus, our son has an Android)
It may fit the idea of degoogling in law, but not spirit. In pretty much any of the reasons you might want to degoogle, microsoft is no better than it here. You are falling for the same carrot again, to feel the same stick of monetization whenever microsoft decides they have grown that product enough. All the while feeding the same data into the same profile of you held by the same information brokers to mess you up now or later in all the ways information that should never have been public may.
I'm sure the extra features are nice though
Evernote seems nice, for basic notes I can also recommend nextcloud, which you might have already and where the fact notes are saved as files also grants you more freedom to use them with random tools or scripts, if you so whish