Do anyone have tips on how to get off the ground for someone whos experience can be summarized to something like 1 hour of fruity loops but who now starts to get some free time? (videos, explanations etc that start from scratch)
If you're looking for a free wavetable synth comparable to Serum from the article, I recommend Vital: https://vital.audio - there's a fairly active community forum there as well.
Subtractive synthesis is different from wavetable synthesis, but most of the concepts transfer. And Syntorial even has a free download (after the initial purchase) which covers Serum specifically, as well as a couple other industry standard synths.
It might be pricey depending on how invested you are in learning, but they have a demo so you can see what you're in for.
From my perspective, outside messing around by yourself, I don't know of a more cost-effective way to learn everything that it covers, and it saves significant time over messing around.
The best advice I was given relating to this exact question (20 years ago) was to invest in a midi keyboard, stick with one piece of software and use my free time experimenting with it. That's it. Watching youtube videos is a complete waste of time in my opinion, since a lot of that crowd has fallen into the trap of reviewing one plugin after another, without really being able to create art. At best it's a circlejerk of mimicry and patterned-knowledge regurgitation.