Leviton has firmware updates available for some of their ZW devices, but (as of Fall '23) the file formats are unfortunately not compatible with HE's built-in updater. But it is possible...
Leviton has a couple help pages on the topic - one here, and a more helpful one here... The latter page is directed at HA, but it includes the update files we HEers need too -- .ota files, specifically.
If you are in Leviton's Beta program (e.g. for the ZW15R), these same overall steps work for those GBL files.
1.) Both pages should identify what Leviton devices currently have updates available. If yours is one, then download the corresponding .ota file at the bottom of the HA help page.
2.) Next, install this updated fork of the original z-wave updater tool: [BETA] Updated binary firmware updater - Custom Apps and Drivers / Custom Drivers - Hubitat. Note: install this as a Driver (not an App)
3.) Next, add the Leviton .ota file to HE's own "File Manager" tool (found in the HE Settings area).
4.) Once loaded in File Manager, right-click over its name and use "copy link" to copy its local URL path. Paste that in Notepad or something similar -- it'll look like this:
Now manually add ":8080" at the end of your IP, so it looks like this:
5.) Go to your Leviton device's Devices page in HE -- change the driver Type to "Z-Wave Firmware Updater" (that's the custom/user driver we installed in Step 2). Then hit "Save".
6.) In the new options at the top of the Device page, there'll be a "Clear Lock" option -- I recommend clicking that. I don't believe that can hurt anything, and it may in fact help a lot.
7.) In the "Update Firmware" option's entry line for binaryFirmwareUrl, copy/paste the 8080 version of the URL you made in step 4.
Click the "Update Firmware" button - the progress should be reflected in the Current States section over to the right. Progress may not be super fast, but it should be steady.
8.) When done, it'll just say "Complete device is flashing..." -- that actually means the update is finished.
9.) You can then swap the device's driver back to its regular driver. If you want to clear out the leftover update-related states on the right side, you can use the Device driver to do that. If you want to double-check the f/w updated for sure, you can use the Basic Z-Wave Tool driver to do that at any time too.