1. I'm not implying that the OP wants to build a business. It's just a fact, most digital nomads living the lifestyle that outsiders inspire to obtain have their own business or are contractors. In the example using myself, I stated I had a 15-year professional career working in tech. This led to creating my businesses. I said it wasn't something that happened overnight. The fact that someone in their 20's, with no career, thinks they can achieve the same lifestyle I and others have achieved, all in a few months is honestly laughable. Here's a direct quote from the OP "What hard skill can I learn quickly to achieve this lifestyle?".
2. When asked in an interview "where do you see yourself in 3-4 years?", you'd be surprised how many people will blurt out their ambitions that equate to leaving after you've invested in them. I've interviewed plenty of people over the years.
3. OP doesn't sound like they want to dedicate time to learning hard skills. They sound like they're looking for a quick fix to live a certain lifestyle now. Hence why others have suggested ideas like working on a farm while travelling.
4. The OP is throwing out comments about learning to code so they can quickly get a job. You don't just learn to code and get a job overnight. You don't just decide you're going to be a software engineer overnight. For anyone who is a professional SWE, it's insulting to imply that doing so can be achieved quickly.

As much as people like to delude themselves that they're going to do a Udemy course that will land them a job in tech, this isn't how it works in the real world. As stated, I've spent 15 years working for FAANG companies.

For a junior swe position, you're going up against people who have studied computer science at university, have been coding for 3+ years, have a large portfolio of work/ projects, and have probably also done internships at FAANG companies. If the OP spends the next 2 years teaching themselves to code, I will say with 99.99% certainty, even if they managed to get an interview with a tech company, they will fall flat on their face when hit with a basic data structure and algorithm question.

At the lower end of the spectrum, let's say the OP teaches themselves web development. The OP then applies to small local web design agencies. They've got no chance without a strong portfolio. All of this takes time to learn and create. The OP would just be one of the thousands of people who can't write professional code who are applying for a single position. Their CV wouldn't even get looked at. Do you know how many people are out there applying for dev jobs who don't even have a basic grasp of OOP and basic design patterns?

As for remote trainiee positions. Any trainiee position for a professional skill like a developer is going to require you onsite.

No one is saying the OP can't choose any of these options as a career, but it takes TIME and requires walking the right path. It requires a genuine interest in the subject. Asking "I want to live XYZ lifestyle quickly, what job is best?", doesn't imply the OP is someone who's going to learn how to code properly.

If someone is happy with a low paid job answering questions on live chat, then yeah anyone can probably find a job like that quickly. However, I wouldn't class that as being a digital nomad. That's just being young and backpacking around. However, once again, the OP is throwing out remarks about quickly learning to "code".

The OP can have any career they want if they have the right skill sets, personal commitment and the will to make sacrifices. However, to disagree with "much" of what I'm saying is an insult to anyone who has built a professional career doing anything.

Want a job in tech as a "coder" but know nothing about computers? How does this basic knowledge make you feel? https://www.a1k0n.net/2011/07/20/donut-math.html

Still think the OP, with no relevant education or experience, can get a job in tech to "learn quickly to achieve this lifestyle?".