I used Apkmirror for Snotes on the TabS3, wasn't fully functional, have it on my Note8 from the Playstore . . . just frustrating that Samsung is letting go of, imho, a more sophisticated app. Will try Apkmirror for the Note10.
Like Cprice mentions, you can side load it--but you don't have to. It's available in the Samsung app store. I'm going to agree with you about it being better (including more sophisticated). I had created some custom templates that are no longer useable in Samsung Notes.
I did get it from Apkmirror, works well, and did see after the fact that it was in the Galaxy (that's what it's called on my phone) Store. Seems like same app. Did try Samsung Notes too . . . definitely lacking compared to Snotes. Mystifies me why Samsung would not keep Snotes officially going, or even adding functionality. How costly could it be to a company like Samsung. Btw, how did you create custom templates?
Custom templates are just images that you create with the information/layout/colours you want. You then import the image to create your template and each page comes up the way you want it. A very "nice to have" feature.