I'm one of the feeds. My window has a high bias to west facing so I only provide partial sky coverage for my region. That said, the whole point here would be not to have single actor dependency. Obviously selective coverage could be turned on but I think blatant misreporting would be apparent.
I compiled the git source on my own pi. Bert knows who I am.
Hi! Galmon guy here. This has only once been a problem, someone with a modified firmware, and that produced some exceedingly strange data. In the galmon design, which is quite neat if I say so myself, data is stored per source. If any data is bad, we can throw it out. If someone would really want to mess with us they could of course. But we're probably niche enough that people don't bother.
Are there even any chipsets out there that can receive IRNSS? I don't think the very common u-blox ones can. It seems like only some Qualcom 4G/5G chipsets support it, which are probably difficult to get on a hacker-friendly add-on board, especially outside India?
Septentrio, Hemisphere and Trimble have boards capable of receiving NavIC/IRNSS, at least. The cheapest module would probably be Septentrio Mosaic-X5.
Digikey lists that module (which is not much different in size/shape from the U-Blox modules) at 675$, so I'm not sure this puts it in the cheap/hobbyist range ...
How about maybe support for GPS extensions like WAAS (used by aircraft to land in US but can be accessed by some consumer devices)