Has Kaspa's pruning been independently verified as safe?

Yes — Kaspa's pruning algorithm is backed by a formal security proof in a peer-reviewed paper on the IACR ePrint Archive (2021/623). Peer review means independent cryptographers evaluated the algorithm before the paper was accepted for publication. The proof mathematically demonstrates that chain integrity is preserved even while redundant block data is discarded — it is not a trust-based assurance but a verifiable mathematical result. For a beginner, this is significant: you don't have to take anyone's word for it, because the proof is public and has been scrutinized by outside experts.