What are some of the more popular non-commercial cultural things you're aware of?
This could be things that once were commercialized but are now public domain, or have largely resisted commercialization to this day. In this context I mean this as aiming for profit and being sold/monetized.
Many board games, such as chess, go/baduk, backgammon, and mancala were played before capitalism or copyright were invented; and thus have always been in the public domain.
Precursors to chess date to the 700s CE, and chess was played under recognizably modern rules in the 1400s. Go may date to the 200s CE, but took its modern form in the 1500s. Backgammon-like games are known from Persia circa 800 CE, and modern backgammon from the 1600s. And mancala games are over 6000 years old.
Somewhat nuanced, but riding a bike anywhere. There have been many failed attempts to license or tax bicycles. The bicycle has been around in various forms since 1817, and in most cases, the laws on rights for cycling are as old as the corpus itself. Once you have a bike, you are as free as you dare or as free as your local independent cycling infrastructure supports.
Maybe doesn't quite fit but tabletop role playing games. Most of everything you need to play is available for free online, even for the popular commercial games. All you need really is paper, dice (sometimes), some imagination and some friends.
Yup. I remember plating Battleship with pencils and graph paper. Great fun, and if your opponent cheats, make them use a pen so they can't move their ships.
Music is pretty popular as a form of culture, and it has historically been a thing shared for enjoyment of culture primarily instead of for profit. Obviously modern music can be commercial but the history of music in general is much deeper than the modern commercialization.
There's a specific app for that? I see people doing geo caching the same way they do that painted rock thing. Can usually find clues and riddles to find them posted on a physical message board at the community center.
Virtual pinball. You can get all existing tables and many more that were dreamed up by passionate fans of the game and it's all shared freely online. I even think it's legal.
Pen&Paper maybe?
yes, i know you can go out and buy DnD modules and books, dice, stuff.
but the cultural part of it seems to me to be just friends sitting together telling stories
Solid fun at any skill level and very modest cost. A round of disc golf is basically an excuse to go for a nice walk while hanging out with friends or even solo.
You can buy a few discs for 10s of dollars and can even share them if you want. Courses are everywhere (at least in Canada, but I suspect elsewhere too) and usually absolutely free. Discs are portable enough to take whenever you visit a new place. If you want to get serious, you can spend a little more, get more discs or a fancy bag, go to tournaments, but it is still cheap compared to almost any other sport and really hard to spend much money on.
I am absolutely terrible, but I get better every time and I have so much fun.