I would treat this as a safety question, not a dating recommendation. For anyone under 18, the priority should be moderation, age-appropriate spaces, and privacy controls rather than trying to match with strangers.
The main things I would look for are strict reporting tools, clear age-gating, and a platform that does not push people toward private chats too fast.
If the app does not clearly state who it is for, that is already a warning sign. I would rather see a platform that blocks suspicious accounts than one that chases signups with vague promises.