The overbought and oversold territory is constant for all crypto assets

When CCI breaks the +100% line, that asset is said to be overbought. On the contrary, when CCI breaks the -100% line, that is the oversold territory. It doesn't matter the type of crypto asset. This interpretation stands for all assets.

Buy and sell signals varies across crypto assets

CCI signal is simply saying that there will be a market reversal very soon. Sell signal can occur when CCI touches or breaks the +100% line. Whereas when CCI touches or breaks the -100% line that is a buy signal.