I have no idea, tbh. Don’t know, where to look for that information other than contacting Fairphone directly.
Those sources to me just seem not really reliable.
In my opinion a wikipedia list in the best of times works to tell you what there is; i.e. what’s on the list supports (is likely to) HD voice, but devices not on the list are unknown if or if not they support HD voice. I never would expect such a list to be complete.
The site Device Specifications names AMR-WB as one of the “codecs usually supported by such devices”.