I always heard that salary data was available in Norway but high end streamers are probably running these funds through a corporation. Does Norway have essentially open books for firms?
For Finland capital income is included in public data. As such doesn't really matter if it is paid as dividends or wage. Ofc, if you hold it in it is bit more complicated, but even then some data can be gotten.
Getting a persons private salary is slightly more arduous thank looking at the income of companies.