For keyboards specifically, there are still community run group buys happening on the geekhack forum.

It's both a lot more interesting and a lot more risky than Massdrop used to be in the sense that there is lots of stuff that even the old Massdrop never would have offered but you're sending a random person on the internet money (sometimes hundreds of dollars) and hoping to receive a product many months later. They have added a "vendor trust" program in recent years to better help inform buyers but there is always risk.

> Is there already something like a successor platform?

I too would like to know. I bought many keyboard build kits from massdrop back in the day as well as my terrific Sennheiser headphones.