Cool! I'm not too familiar with Go, but I have a weird affinity for custom elements. I wish that I'd see cool projects that involve them more regularly, but the community seems relatively insulated. I'll have to take a deeper look at this later.
Seems like the standardization effort has stalled out. Did React kill the perceived need for it?
Web components are a bit low-level, so you have libraries and frameworks like Polymer, X-Tag, Svelte, SkateJS building on top of the standard to make the development fun and friendly.