Really cool seeing this new HTTP standard, I bet it'll help a lot for large resources like video and pictures.
https://datatracker.ietf.org/doc/draft-ietf-httpbis-compression-dictionary/
I discussed a similar idea on my blog without knowing about all the efforts to standardize it:
https://sethmlarson.dev/http-header-compression#allow-origins-to-manage-their-own-static-table