Ask HN: Should I join a biotech startup as the first engineer?

Hey, So just like the title says. About me: I'm a junior developer. I've worked at 2 startups before, both building the main backend infrastructure, usually with a small team to start with. First time 3, second time 4. I’m pretty familiar with scaling a company to suit certain needs. 4 YOE total.

Company: The company is a biotech company that deals with image processing.

My concern: I would be the first engineer. They have a lot of technical debt, they've been very hacky with the process and just doing things that are not quite scalable. I would be the first engineer for about the first year, so not any mentorship.

Despite this, I’m interested because I think this is a space that I am not familiar with but have a lot of interest in. I was very upfront that I will definitely be slow, they are just happy to have anyone on the team. I’m relatively young so I’d really like to take a risk like such, but do you think it would be better to continue to build YOE at a big company? Just, I’m not sure if I would get an opportunity like this again. I like the idea of being “uncomfortable” and challenging myself. tl;dr: With 4 YOE should I join a biotech startup as the first software engineer?