There arenāt any specific crypto ETFās as they arenāt currently allowed to be sold to retail investors here in the UK. The nearest thing possibly could be one which the underlaying assets would be based around companies in that sector (eg. miners, etc), this may not be what you want though.
Regarding minimising cross over, itās worth having a read though of this topic:
A good bit of useful information and ideas - as always though, do your own research.