it's not a waitlist, simply invite only. If you can find someone who browses tildes they can give you an invite with no issue. But a semi-common way to "go around" that is messaging the admin, who ofc has infinite invitess, has a business address, and probably has dozens of requests coming in to read.
it's quite the opposite here. The lack of free account creation is to purposefully limit growrth. Tildes doesn't want to be a dumping ground for reddit refugees everytime a drama explodes.