Huawei recently held its own in-house Analyst Summit for 2019. During a Q&A at this event, its representatives reportedly confirmed that Apple has not responded to its proposal to sell it the 5G modems it needs for its iPhones. This offer had recently been made publicly, possibly to highlight the fact that one OEM can use next-gen radio bands and the other cannot.
https://www.notebookcheck.net/No-Apple-has-not-taken-up-that-5G-modem-offer-Huawei.418083.0.html
If a phone has a 4G version and 5G version with all else equal, I would definitely choose the 4G version. It would be cheaper and consume less power, and there's effectively zero 5G coverage and not that I particularly need the additional speed.