What's the latest Windows 10 Mobile version I can get on my Lumia 1520?

I have a Lumia 1520. Can I update it further? I'm on Windows 10 Mobile and it says build 10.0.14393.2551 - I thought there are further higher builds but Update isn't giving me any (either on the phone or a standalone app that I used to update it past 8.1).

I tried enabling Insider Preview builds but it says I "need to upgrade to a newer version of Windows" to get those (but as noted above, I can't).

Is there a way to officially get further updates? I don't particularly want to do things like changing the device identifier to trick it into installing a newer version (as I assume that may create some instability) but not really sure.

EDIT: I used Universal Updater (https://github.com/fadilfadz01/Universal_Updater) on a Windows 11 machine (virtual machine running on an M1 Mac technically but I don't think that matters) and was able to update my 1520 all the way to Build 1709.