I'd say it's more common for people to not have an online presence than to have an online presence. Working at a FAANG, the vast majority of social media from the employees I've seen have nothing to do with technology (probably for risks of saying something they shouldn't say as an employee of a publicly traded company).

I do know a personal friend who pivoted from english teaching to startups to FAANG and he was kind of smart. He made a podcast in his field, but when he became a manager at a FAANG, he deleted his podcast.

The most important thing in your early career is to work at the right places or the right opportunities. If you're early in your career I don't think your portfolio or LinkedIn is going to matter than much to be honest.

If I was young and starting out today I would focus on:

a. An internship if I was in college with a great company. It's the easiest way to get a job at a FAANG or whatever industry or place you ultimately want to work in

b. Contributing to some llm or technical crypto project where there's demand for people to contribute and you can make an impact because the market isn't crowded. Avoid the easy tutorial copy/paste stuff and push some code in a technically interesting and useful project. You'll learn a lot and make valuable connections as a lot of these people are usually established

If you have to pay bills, you can get whatever job you can find today, but while pursuing a & b to maximize opportunity. There's also communities you can join where you can potentially get referrals, but being very clear on what you want will help you tailor your experience.

Most "professionals" with an online presence use it strategically and are only showing exactly what they want you to see