This is not quite right. levels.fyi has data for all companies that have enough submissions. For historical reasons it has a lot of data from well-paying tech

This is not quite right. levels.fyi has data for all companies that have enough submissions. For historical reasons it has a lot of data from well-paying tech companies in SV, but it also has 167 data points for SWE compensation at Accenture (which is pretty far from the "best compensation" you can get). The median on levels.fyi is probably higher than the true median, because well-paying companies are overrepresented (people who work at those companies tend to be more plugged in, etc), but most companies that have a sufficiently large number of developers will have enough data points listed that you can get useful information out of it. Heck, there's 69 data points for SWE comp at Nordstrom!