The amount of state that early video games stored in like 256 bytes of ram was actually quite impressive. I bet with some creativity one could do similarly for a web app. Just don’t use gzipped b64-encoded json as your in-url state store!
I just used Pako.js which accepts a `{ dictionary: string }` option. Concat a bunch of common URL together, done.
The only downside (with both our approaches) is if you add substantially many new fields / common values later on, you need to update the dictionary, and then old URLs don't work, so you'd need some sort of versioning scheme and use the right dictionary for the right version.