Camo (by Reincubate) is the app they’re copying. Camo is awesome. It does color correction, cropping, zooming, a ton more features. Also works on Android, Windows, and many combinations of devices. Worth checking out.
To remove watermarks or use those features you mention you need “Pro”.
Pro costs $4.99 a month, $39.99 a year, or $79.99 for a lifetime license.
I hope they survive.
They have the advantage of working with older devices like the iPhone 6S and iPhone 7, both of which have excellent cameras that are better than most webcams I've tested them against!
I also doubt Apple will include the other video tweaks you mention.