Yes, but only if you migrate from ~/.ssb to Manyverse's own folders.
Typically, SSB apps on desktop such as Patchwork, Patchbay, and Oasis all share the same ~/.ssb folder, and thus you can use the same account on all of them. Manyverse cannot run on the database that is at ~/.ssb, because it uses a new database that is incompatible with the other apps.
When starting up Manyverse, you will be asked to make a choice between:
Creating a new account. We recommend this if you may want to keep using Patchwork as usual.
Migrating from ~/.ssb. Not recommended, but it works correctly and you can transfer your existing SSB content to Manyverse. It's important to know there is no going back, unless you open Patchwork to create a fresh account.
Read here about why the migration is necessary.