Development of UHF systems (i.e the 400 Mhz's) is continuing apace.
In summary, LoRa (Short for Long Range) is looking good with telemetry a significant benefit.
For model submariners, commercial equipment supply is the problem. openLRS equipment is now very rare. Home built LoRa equipment is not too difficult but it would be nice if there was commercial interest. Tim Senecal reports on tests on commercial LoRa in the link below. (BTW I have heard that supply of 40Mhz equipment may be getting easier soon, which is still a good system for most submarine modelers)
All the detail over here:
https://www.theassociationofmodelsubmariners.com/t83p250-uhf-radio-control-for-submarines-openlrs-lora-fsk-etc-on-458mhz-and-433mhz#11719