I'll list a few non retarded leftist spaces off the top of my head
9chan.tw/leftcel
bunkerchan.live
dismantle.capital as based anon>>422 mentioned
Unofficial Leftypol fbi.gov (ye I know fbi.gov is a botnet surveillance application with transhumanists all over but ULP has some decent users who can make a fine addition to leftychad.net, some have even used leftypol since 2016)
As
>>420 said we can raid leftist subreddits and rake in based users and make the radlibs cry, we should def put this plan into motion