The IndieWeb is a loosely organised group united by a simple yet somewhat utopian idea: you should own your web presence. Have your own domain. Add your own content. You can push this to silos if you want, like twitter or facebook or a fediverse instance. But ownership should never be in question. If the fediverse instance goes down, or twitter or facebook block you, that content should still be there for you. On your website.
In practicality these meetings, of which I've attended a handful, are open discussions about website building, tools to use, methods for synchronization, archiving, styling, protocols... today we even segued to the topic of having a solar powered wifi hotspot serving your site on your tombstone, in the untimely event of your demise.
That might sound a little bleak, but what I meant to say is that it's a nice group of people interested in expressing their ideas and trying things out. From hosting websites on Netlify or GitHub Pages to building a connected thermal printer that prints all the webmentions your site receives, integrating your site with IndieAuth, building search engines, or finding out what MicroFormats are and if they're useful for you.
In a way I find that geminispace (and gopherspace, I assume) are mostly philosophically aligned with the IndieWeb. We use our capsules to express ourselves, and try things to find the boundaries and possibilities within our spaces.
The similarities are probably why I like them both.
All planned events are listed here.
-- CC0 Björn Wärmedal