CRYPTOCURRENCY

Can cryptocurrency be used as a source of down-payment funds in a purchase mortgage transaction or for reserves in a refinance transaction?

Without answering your question - two questions

What is the value? Cryptocurrency is very unstable. What may be worth $50K today may be worthless.
How does the bank control it? (access it)

I think that is a business decision unless you are talking secondary market.

This is an asset quality issue that's bound to attract safety & soundness regulators' attention. Have they said nothing about it in exam manuals or industry guidance releases?