Pinterest is a solid pick, the buyer intent there is underrated.
The one most people sleep on is Telegram. You're reaching people who already joined a niche channel about your exact topic, so intent is high and you can warm them in DMs instead of fighting an algorithm. Pair it with short form video for the top of funnel and Telegram for the close, and you get reach plus conversion in one loop.
Whatever you pick, match the platform to where your offer's audience already sits. That beats chasing whatever is trending.
Best,
Floqal