Initially, desktop websites were considered the primary version and mobile websites were the alternate version for businesses, but following search behavior and trends of mobile searches, this has changed and Google decided to introduce mobile-first indexing. What it means is pretty simple, if your website has a desktop and mobile version, the mobile version will be indexed first, which means for it to rank, it needs to follow the SEO best practices. If your desktop is ranking well, and your mobile website is similar in layout to the desktop version, you just have to ensure that it is responsive to ensure that it ranks as well. Of course, they are searchable. If a query is made using a mobile device, Google will display your mobile version to users.