I haven't tried those themes because they are made for Gnome. They use the font DPI value so they should work (as far as I know) in any GTK3 environment.A major (personal) achievement is the creation of a gradually scalable version of Nextwaita.
By using 'Gnome-Tweaks/Fonts/Scalable factor' you can change the scale of the interface:
Setting this scale to 0.92 (for example) will scale the theme down to a level suitable for low resolution screens.
Setting the scale to 1.35 (for example) will scale the theme up to a level suitable for high resolution-screens.
This theme will change its buttons, radio-and checkbuttons, sliders, switches, and general padding accordingly.
While gnome already tries to scale, this theme does it better. This is done by using (relative) REM in some places instead of (fixed) pixels.
https://www.gnome-look.org/p/1289376/
https://www.gnome-look.org/p/1293734/
Since GTK developers don't intend to bring fractional GTK3 scaling to X.org, maybe themers can make it work?
I feel tempted to boot into MATE and see if it works there, but it may have to wait until tomorrow.