stop wasting your time and buy $20 worth of bitcoin already! that is a much faster way of reaching your goal to "start trading" as you put it.
This. If you're going to spend that much time and effort to earn $25 in crypto anyway, why not just spend that time to earn $25 in cash directly? With the same amount of time invested, I'd bet you'd earn much more doing your job than what you would have earned hunting airdrops and bounties. Go work overtime or something. You're exchanging your time for money either way, so you might as well make the most out of it.
(for reasons of anominity, so also no stuff selling etc...)
If anonymity is the only reason you don't want to buy, you could create a throwaway account and trade with a random user. You won't need an account in an exchange, and you won't need to reveal your identity. I mean, if you want to trade the crypto you earn in the future anyway (according to your topic title), this shouldn't be too big of an issue.