Just a point of order: the closest thing I've seen to telemetry from GL.iNet is related to pinging their update server to notify of new firmware releases. That may have changed since the v4.6 series but they seem to have enough on their hands already before totally nuking their reputation for VPN/privacy-oriented devices. I say that after scanning days worth of .pcaps via tcpdump with WireShark. tcpdump should be available in the default GL.iNet opkg feeds.
Well, I'll put it like this. 'Domino', the (old? -- it may have changed in the years since) GL.iNet Web GUI on these routers make use of a custom API & even more scripts that aren't compatible with stock/'pure' OWRT. For example:
If your primary motivation is for a web GUI you can work with, I'd just flash pure OWRT. You'd be giving up Domino, GL.iNet support, and, as stated probably take a noticeable performance hit on at least the VPN-side of things if not Wi-Fi. The Qualcomm SDK for these SBCs aren't open source. It's not just OWRT GL.iNet builds on.
I hear 'Argon' is a pretty popular theme but I don't chase trends though I get a custom dashboard is always nice. I need my travel router to work so I can work. If you're going to get all 'experimental' with yours be sure to read up on how U-boot works in the GL.iNet online docs so you can recovery in a worst case scenario. For lesser scenarios you'll probably want this:
But before you fawk around and find out you might be interested in this:
As you say, to each their own... & it's your kit. Just make sure you have an escape hatch if/when things start going belly up.