Starting a new ecommerce business, a bit confused on taxes (Maryland)

Sorry if this is a dumb question. I'm probably overthinking it.

I'm starting a new FBA (Fullfiled By Amazon) business out of my home in MD. I'm forming an LLC. I'm not 100% sure which licenses I need in MD other than a state sales tax registration for MD and probably a trader's license. I also don't really understand the nexus I could have with other states. Due to Amazon having almost complete control over my inventory, it could be anywhere. I can't imagine that I would have to register in each state.

Do I only need to be registered in the state where I will be physically operating from (in this case, MD)?

What type of professional should I seek services of for help on this end? Tax lawyer? CPA?

I posted on r/smallbusiness but didn't get much help there.

Thanks