There's also JRPN [1], not sure how closely it follows the original HP-16C as I've never used the original but it seems to give significant thought to it. It's

There's also JRPN [1], not sure how closely it follows the original HP-16C as I've never used the original but it seems to give significant thought to it. It's written in flutter so available on linux and android. [1] https://jrpn.jovial.com/ https://jrpn.jovial.com/