When I first turned pro 17 years ago, my personal portfolio of projects dating back to high school certainly made a difference. 10 years ago when I moved to SV and joined a tech startup, it was my open source contributions that made the difference.
Granted it was a simpler time back then, but I fundamentally believe in the idea of scratching ones own itch and showing the world. Maybe things are saturated now, and you won't stand out as much, but I still think shipping is the ultimate litmus test. If you can ship stuff by yourself that's one of the most powerful signals, and we are very fortunate how easy it is to do that as developers in the modern age.
A lot of startups are aping Google/Facebook and trying to get the absolute smartest engineers they can find by casting a wide net and then aggressively culling so they end up with what they believe are the cream. If you really want to get into one of these then you need to practice algorithms and whiteboarding, you can improve at it. That said, passing a high interview bar says very little about your real value as a programmer. Companies like Google and Facebook have amazing technical knowledge and to work on, but your individual impact will rarely be detectable. And if you're not careful you end up with the golden hand cuffs in the sense that no other companies pay as well, and you won't really learn the hustling skills you need if you ever want to do your own thing.