Is Amazon worth it for me?

I own a brand that has been decently successful for 5 years. My business is in the accessories niche. Thing is I’ve only ever sold on Shopify and no other platform. I have been considering Amazon recently but I’m not sure if it’s worth it.

My main questions are:

As I already have a trademark, how long would the process take for brand registry & the are the benefits of brand registry worth it?

I would like to fulfil all the items myself rather than FBA, is this a wise option?

Thanks!