With the Redmond or Chicago95 theme for GTK, those apps also look in place in case you need them.
For truly a low resource usage desktop I look at LXQt. Same base lib as KDE, namely Qt, which is apparently a lot lighter on the resources than GTK. Not sure if it is ready yet these days.
https://www.opendesktop.org/p/1253201
With the Redmond or Chicago95 theme for GTK, those apps also look in place in case you need them.
For truly a low resource usage desktop I look at LXQt. Same base lib as KDE, namely Qt, which is apparently a lot lighter on the resources than GTK. Not sure if it is ready yet these days.