@vlagged Brilliant!
Thank you for that and for de-noobing me.
For other new users, if useful, I did:
$ devel-su
$ pkcon install zypper
$ zypper ar https://repo.sailfishos.org/obs/home:/b100dian:/commhistoryd/sailfish_latest_armv7hl/home:b100dian:commhistoryd.repo
$ zypper ref
$ zypper up libcommhistory-qt5
Installed Patchmanager, rebooted.
SMS in and out work, MMS in and out work (wifi).
It complained about repomd.xml and packages being unsigned.
That’s expected, isn’t it?