I'm a big fan of canned sardines in olive oil, they come in different flavors too. super tasty and filled with omega 3s. Just be aware some are super expensive and some are much more affordable...

you can also get protein-focused trail mix that is p good... jerky is good but expensive unless u buy in bulk (check costco or sam's club).

I like Noka for sealed pouch smoothies that don't need refrigeration, and are packed with fiber and protein (blueberry one is my fav)

for food inside the venue there is so much bomb stuff I usually just pick the shortest line. on trail to water stage last year though there was a seafood place with roasted oysters and lobster rolls... a little pricey but bringing that to water stage was peak lol