Generally speaking, large positive net flows lead to higher prices. But the presence of these flows is only possible due to the way ETFs are constructed. As explained here:
ETF shares are created when an “authorized participant” deposits a daily “creation basket” (or cash) with the ETF.
ETF shares may be redeemed through the reverse of the creation process. That is, an authorized participant presents the specified number of ETF shares to the ETF in exchange for a “redemption basket” of securities, cash, or both, which typically mirrors the creation basket.
This creation and redemption creates traceable flows, but this process is not repeated in other instruments such as Bitcoin. There are some Bitcoin ETFs planned, but even when we have flow data for them, the flow data does not always correlate to price.