How does this compare to a lightweight Linux distro like Lubuntu?
My vastly less powerful Manjaro arm Laptop with the same setup idles at 160MB.
Most of the RAM seems to be used by systemd btw.
memory was basically a non-issue unless i was trying to compile a large package, i don't recall the precise baseline it had after boot but it was probably around 12-25%
I can get a fully functionable desktop with GUI apps, generic hardware support (i.e. not locked down to my hardware), support for dynamic modules/drivers/libraries, audio, 3d-accelerated video, and more in a 300 MiB footprint (with only basic iso image compression) and runnable with 128 MiB of RAM.
Then comes in the last part of your statement: "do some very basic web browsing." The system above works just fine with a browser featuring < 201x tech, with great CSS, JS, HTML support. But if I need to build and bundle the latest Firefox, Chrome, or whatever without manually stripping out a ton of features (beyond what is available via distro package managers), that footprint triples or quadruples in size and the memory requirements skyrocket.