Based on the mention of “Any and all developers” in the OP & “All members of the community are invited to join” in the group’s description, it’s likely to remain open for any user on the platform. I tried joining the group on my alt, which has never logged into the Developer Forum, and the account was accepted immediately.
CC @jmkd3v
@Crazedbrick1 posted an extremely high quality version a while back, in addition to the logo without the gradient:
