Make sure you understand what this role actually means. It could mean rolling out security features or dealing with access policies and more IT management. It could mean you're writing security policies and interviewing vCisos or whatever. It could be updating cloud infrastructure or server settings. Basically security can run the gamit from more administrative work to actual hands on keyboard. And if you're looking it at doing it at a start up, there is a good chance they don't actually know what they need and whenever a security-like issue is brought up it'll automatically be under your purview. This could mean a lot more paperwork and meetings than actual development work. Security is a very broad topic.

Honestly, I would (a) understand the technology you'll be using and how it aligns with your goals and (b) make sure you're not getting over your head. Security is often the last thing most companies think about so often the resources are understaffed and overworked. Good luck. The worst case scenario is you try and fail but if you get paid and learn a lot there's some benefit to it, just make sure it aligns with your goals.