See https://manifold.markets/post/public-randomness-sources for my post on current methods. To resolve YES, there must be an easy-to-use method that allows generating random numbers quickly (within at most 1 minute), and it must be possible for everyone to be fairly confident in the fairness of the random numbers with little effort, and highly confident in the fairness with more effort.

Note - this is deliberately a pretty high bar. A simple bot that generates random numbers on request with a local RNG, run by a trusted operator (e.g. Manifold itself), would be perfectly sufficient for most purposes, and people are already planning to write one, but this question asks whether we'll be able to go one step farther and not have to rely on the security of that bot.

Security criteria: the RNG must be reasonably robust to exploitation by any actor or group of actors with a budget of less than $1m USD. (So something based on a popular blockchain, Cloudflare's drand, or NIST would probably provide sufficient security.) Exploitation here includes leaking RNG info in advance or manipulatability of RNG.

Verifiability criteria: For example, showing a record of previous random numbers on a website, or posting them in an automated comment, would suffice for low-effort verification. Using a cryptographic mechanism like in blockchain, drand.love or https://beacon.nist.gov/home would mean that anyone can (with high effort) verify with high confidence.

Also note - it is entirely possible that something satisfying these requirements already exists somewhere. For this to resolve YES, someone must find it and let me know about it.

Related question that does not require strong security: