I wanted to describe my personal experience in case it shifts anyone like me towards applying. I was accepted, received travel support, and went to EAG London last month.
Initially, I considered the likelihood that I would be accepted and be able to go very low: I didn't think I was involved enough in EA and I didn't think it made sense for me to receive travel support to go as I live very far from London. I also didn't think that I 'deserved' to go: I reasoned that I shouldn't take a spot from someone more engaged in EA or could provide more value to other attendees. I probably wouldn't have applied if not for having a personal connection with someone else who applied.
Nearly every interaction I had at the conference was positive. Many people I spoke to were happy to share about their area even if I had little prior understanding, and I was surprised to find I had ideas and perspectives that were unique/might not have surfaced in conversation had I not been there.
As a young person, I have never felt more respected as a full person and equal with meaningful ideas to contribute. EAG is intense - it can be near constant interaction with a lot of people, focused on the most important problems in the world. But going to EAG made me feel like a 'part of' EA, and gave me a lot more confidence to make decisions, to try things, to reach out to people.
If you're like me and concerned about not being qualified or not having done enough, let the organisers judge, and consider the possibility that EAG might give you the ability to do more later.

Also, if you aren't sure, apply! It's the organising team's job to decide who attends so apply to as many as you want and let them decide.