There’s quite a few alternatives to Pinterest, but many are just bookmark managers (like Pinterest is anyway). Pinry is probably the closest one to Pinterest.

There’s a couple of capcut alternatives: OpenCut, FableCut, Shocut and Kdenlive.

Monica and Meercat CRM are decent options.

I also maintain one at openaltfinder.com, although it’s specifically designed to find alternatives to proprietary software.