Confirmed, manual installation of the dependency libtinyxml2-2v5_2.2.0-1.1ubuntu1_amd64.deb renders procalc_1.0.5-0ubuntu1_amd64.deb installable.
It's still the case that no installation package is offered through the itch.io client's install button, even after restarting the client - will recheck after next reboot.
Thank you. Now counting backwards from 10.