I gave a talk at BAD Camp this week on declarative (read: server-side rendering) Shadow DOM. One day this will replace React.js. And I learned so much researching this soon-to-be widely available tech; its "newly available" now and will officially be "widely available" in February 2027.
I posted my slides in the presentations section of my website and will be doing this talk a couple more times this year in Vienna and Japan.