[TicklishTiger]

Instagram does not make you sign up to browse.

https://www.instagram.com/explore/tags/ycombinator/

This seems to be the url to browse tags on pixelfed.social:

https://pixelfed.social/discover/tags/ycombinator

Unfortunately it wants you to sign in.

[beardicus]

It looks like you can at least view profile pages without logging in. Here's mine, as an example:

https://pixelfed.social/beardicus