This mirrors my experience quite a bit. Hobbies that involve creative thinking and leaning on each others' skills are incredible at creating lasting social bonds which go beyond the hobby itself. For me that's music (creating it) and tabletop gaming (especially D&D or any similar RPG).

Meeting others through those activities and then gradually building upon the relationships via other social outings, dinner parties, weekend trips etc.

I'm also introverted but learned early on in life that it often just takes one person instigating things to rally a whole group.