I kept trying to sign up from day-1, and kept getting 405 errors. Is that because I was trying on PC?
Correct. The PC option is not available yet. Truth Social is only available on the iPhone right now. Android and PC versions will be out shortly.
As for the iPhone version, it's beginning to grow rapidly. Over 32,000 new users were added since this morning and the total number of active users is approaching 700,000.
The floodgates appear to be opening so those million plus people still on waiting lists should not have much longer to wait.
Not bad for a platform that is barely a month old and still in "beta" mode.