Hi and welcome to R2R, you have to start somewhere and if you budget says start with a Nano tank a Nano tank it is, like someone suggested they are a little more maintenance with being small like water evaporations and you would have to top it with Ro water, keeping an eye on the salinity but it’s a good start to get into this hobby, always learning and hey there’s plenty of people here to get help and advise from, good luck
Welcome to R2R!!! A lot of us come from freshwater tanks. Saltwater tanks are more expensive and we do face more challenges along the way, but it's so much more rewarding! You have a great group here on R2R to help you along the way!