VOIP over LTE has been rock solid in my experience with T-Mobile on the east coast. I regularly get on (hands-free) VOIP Zoom calls during my 20 mile commute and almost never have any latency or packet loss issues.
LTE latency is more than adequate for VoIP, with RTT latency to the tower being around 25ms. Adding another 40, 60, whatever, internet latency for VoIP is still well within the realm of good call quality.
Fair enough. I must have a shitty network. I see 150-200ms pings through LTE with occasional spikes up to 500ms, and any VOIP is both poor quality and we end up talking over each other because of the latency.