Got it, thanks for the hint! It's been around for a while, just released it publicly. You can find details on the bitcoindev mailing list. Feel free to look into it to see if any devil hides there :)

You'll also find a Q&A on the website: https://v1.penlock.io/en/

Hi @jimmysong, mind covering Penlock again? I read your letter so I remember you checked it out last time, it was pretty cool to see. We finally completed the public release, could use the push! Also, I'd be glad to answer any question for you! (bitcoindev link: https://groups.google.com/g/bitcoindev/c/8LkdxVc_nI0/m/ggNzdX1NAwAJ)

Someone shared about the beta last year, and there was a few comments under it. That inspired me to announce it myself this time. :)

Multisig is generally more secure—using hardware wallets from different manufacturers protects against firmware vulnerabilities. However, multisig requires more technical expertise, involves managing wallet metadata, and is protocol-specific.