Interesting, looks like about two grin weeks traded in less than one day, for two BTC. The price surged from about 100sats to about 200sats and came back to 120sats without volume again. I guess the liquidity just drained this time.
I think if there would not be technical obstacles some grin owners would start to provide some liquidity. Perhaps up to 10% of their stock. High liquidity would probably give incentives for 51% attacks. High liquidity would raise overall usability as a currency. Usability would raise the value, but attacks would lower the value of grin.