My Native macos app was using well over 1gb the other day, while my electron notes app was 1/5 of it. Theres an electron tax for sure but people are wildy mixing up application architecture issues and bugs with the framework tax.
It's a RAM issue all right - browsers are set up in a multiprocess manner to allow sharing resources between tabs while sandboxing every single one.
So the footprint of the whole browser might be heavy, but each individual tab (origin) adds only a little extra.
Unfortunately both Tauri and Electron suck in this regard - they replicate the entire browser infrastructure per app and per instance, with each running just a single 'tab'.
And I share your concern for both disk space and RAM - but the solution here is to move away from browser tech, not picking a slightly differently packaged browser.
I'm pretty sure Tauri uses almost as much RAM, you just don't see it because it gets assigned to some kind of system process associated with the webview. Most of the RAM used by a browser is per-tab.