Got Lively (formerly Jitterbug) flip phones for my mother and mother-in-law. The only way to load contacts in the 176-page user guide (UG)¹ is type them one at a time via the number keys on the phone.
Lively is able to pre-load contacts if the phone is bought direct from them. It has no SD card port, so I suspect they do it through the USB-C on the side of the phone. But I couldn't get anything from them other than the intolerable method in the UG.
Called the manufacturer, Alcatel, and got someone who not only couldn't understand the script he was reading, but had trouble understanding me. Started reading a process that sounded plausible, but when asked about the program on the computer, said, "no, the USB is all you need."
Would welcome a pointer to anything online that might help. I can create VCF or other formats from the older phones. I don't have Windows, only IOS, MacOS, and Linux. Been retired seven years but can still write code if I have to.
¹Takes that many pages to document the "easiest phone to use"?!?
Sitting here with a Jitterbug2 flip and a binary list of almost 100 contacts for my mother. And it looks like you got no answers on how to import a delimited contact file into the phone. :(