There is another way … but you’re not going to like it.
Assuming that you have a Microsoft Windows computer available …
sync the contacts from the iPhone to Microsoft Outlook via iTunes (happens automatically when you plug the phone in to the Windows computer)
then go into Thunderbird under Windows and have it import contacts from Outlook
then export contacts from Thunderbird as an LDIF file
Actually that’s where I stopped because an LDIF file is good enough to drive an LDAP server and any half decent mail client can pick up contacts via LDAP. However perhaps your mail client can import directly from the LDIF file if you don’t want to run an LDAP server.
I had to do some data cleansing.
Well, it was better than re-entering hundreds of contacts.
Also, actually that’s from memory of the not so recent past, and so I may have garbled a detail or two - but hopefully it gives you some ideas.
I guess it’s just a matter of who you want to drop your pants to… MSFT or google. Blah.
Numerous other little hurdles for me with Ubuntu- browser is incompatible with a Kijiji (bit surprising), and now Wire messaging doesn’t display properly, making it really annoying to use. The OPO will call and text fine, but so many other details have killed it as a daily driver for me and I lack the skills to fix any of them. The camera can barely focus too so it’s hard to take a quick pic of something to reference. So, that’s why I was wondering if the Librem 5 is ready to roll yet with Nextcloud for my essential needs. I’m willing to ditch the OPO, drop $1000 CAD, and wait six months, on the condition that the phone can do the basic tasks for my needs.
The approach that I am describing does not require internet access. It would not be easy for Microsoft to exfiltrate your contacts.
If you are truly paranoid, you could set up a new Windows computer, carry out the above procedure, then securely erase the disk on the Windows computer (or physically remove it).