To register in Shopee, you can apply through normal channels.

Generally, it is the Taiwan site and the Malaysia site. For the Taiwan site, you can be an individual business owner, but for the Malaysia site, you need a company account.

Another one is the Brazil site. Some time ago, the application for admission was relaxed, and you can also apply for the first site.

As far as I know, for other sites, the system issues admission applications based on the performance of your store, and individuals cannot apply on their own initiative.