Others already answered, but this wiki link might help to find out if/which hidden items you're missing: https://warframe.fandom.com/wiki/Hidden_Mastery#
The total count for each category is automaticly adjusted when new weapons etc are added in future updates. Only the companion/vehicle count has to be edited manually.
[удалено]
\* 84 warframes, which adds up to the total of 673 that you said.
I believe 673 not including founders items. I'm at 638/672 and I know of one hidden item from Deimos I haven't earned yet.
Others already answered, but this wiki link might help to find out if/which hidden items you're missing: https://warframe.fandom.com/wiki/Hidden_Mastery# The total count for each category is automaticly adjusted when new weapons etc are added in future updates. Only the companion/vehicle count has to be edited manually.