The community over at XDA-Developers is a little less voracious these days. There are a lot of reasons: an ever-expanding selection of Android phones means it's harder to make a modding nexus for each one, general improvements in hardware and software make rooting less necessary, et cetera. But those tinkerers can still get some fantastic results. Case in point: it turns out that it's totally possible to get the unlocked HTC 10, currently being sold free of contracts and carriers from the HTC web store, to operate on Verizon.
That may seem somewhat redundant, since Verizon is selling a carrier-branded version of the HTC 10 anyway. But here's the thing: Verizon's branded phones continue to have locked bootloaders, and it's getting harder and harder to crack them. So buying an unlocked phone that works on the network is a huge deal for root and ROM enthusiasts, who have only a few carrier-agnostic Nexus and Motorola models to choose from for full Verizon support. It helps that the phone can go with you should you choose to leave Big Red (which is getting more and more attractive all the time, since they don't seem to be letting up on the evil).
The modification is relatively simple; anyone who's ever rooted their phone or flashed a developer build should be able to do it easily. First you'll need to unlock your bootloader via the HTCDev program, then achieve S-OFF with a third-party tool like this one. Then connect it to a PC and flash a Verizon radio file with the usual fastboot commands. Pop in your active Verizon nano-SIM card, then reboot the phone and enter a command on the dialer app to open the radio selection menu. Pick "CDMA/EvDOGSM/WCDMA/LTE Auto," and your phone should automatically connect to the nearest Verizon tower.
Yes, the unlocked model is using Verizon's full CDMA-LTE network (not just the LTE bands) and no, advanced calling features like VoLTE won't work. This modification might make it tricky to get over-the-air updates in the future, but it should be possible to reverse the process and return to stock with the default radio, then flash the Verizon radio and select the operation mode again. It's not a difficult process, but be sure to follow the instructions below carefully. Congratulations to XDA users "Dottat" and their helpers on the accomplishment!