A related question:  if a taxpayer buys or sells shares in a trust - GBTC specifically, Greyscale Bitcoin Trust, an investment vehicle that owns Bitcoin - is that considered a virtual currency transaction for the purposes of that question?

GBTC and other similar holdings can be purchased through traditional brokerages like Schwab.  Schwab said they 'believe' the ownership of GBTC is treated as an ETF.  Not that GBTC is an ETF but it functions like one.