Wow, both quite interesting. I love that szdt is in active development and to see many similar themes like delegation and DIDs is a good sign. Do you know if either has a working PoC? Once I finish proof-reading I plan to implement something.
There are two other protocols that may interest you
Szdt https://github.com/gordonbrander/szdt
You can find it on Bluesky
or Mosaic https://stevefarroll.github.io/mosaic-spec/index.html
Discussion
I haven't seen any POC, or another protocol is https://github.com/pubky/pubky-core they have a poc but I think it's invite only for now
I played around with pubky when it came out. I found the Bittorrent DHT stuff interesting as a short-term decentralized storage mechanism but had concerns with MIT licensing of core apps. GPL-like is important for a community to know they'll be on an even playing field with corporations. In any case, I wish pubky well and will be interested to see how it's developed.