I currently live on a boat. Dealing with captive portal bs from the marine is always a nightmare. You have to buy the correct wifi extender/repeater otherwise you have to connect each device directly to the network.
While bits and pieces of this can be found implemented in different repos, there seems to be a gap for a software which does this minimally and generally enough and could provide a base for the community to crowd-source profiles/configs/scripts.
It worked with occasional hick ups, but in the last few years I could always use as many devices as I needed (usually two) for free, and the captive portal support on the Fire TV stick improved, so I haven't had the need for it anymore.
I hope the dish is gold-plated…
The gl.inet firwmare itself has a lot of missing updates and I am yet to successfully make custom builds of it (though in theory it should be possible through what's on their public Github repos, save for a handful of packages they provide as binary-only). They do not respond to issues or PRs on GitHub.
I should have taken better notes on building a firmware but I think what eventually allowed me to replicate and make custom build was to just build as if a normal openwrt dist from https://github.com/gl-inet/openwrt with a fork of https://github.com/gl-inet/gli-pub. Ended up ditching their custom hacky wireguard/tor functionality and mostly treating it as an openwrt dist.
Still stuck on a fork of the custom 19.07 (4.x kernel) for E750 (despite my efforts to bring it to 21.02). MT1300 doesn't seem to have had any issues on vanilla openwrt 21.02, though.
The mwan3 stuff can be worth keeping and extending on using the uci module, though.
It really is a shame as there are so many great things with the E750 and it has potential to be the perfect travel router. If there is anyone else who wants to take this to the next level, I could be down for making this ore structured and collaborate on making a more open, accessible, secure and hackable dist either just for the E750 or glinet in general.