Is it possible to know at any given point how many chips are left in the private sale?
Yes it's very easy. You can check it from this address:
https://blockchair.com/bitcoin/address/bc1qy330f4q0fnavnw66lzysrx583ts0the7yyx049xclrs2zq52g87s4fy5xyAnything from:
0 to 1 btc is considered for private sale. (total allocation 2000 Chip as buy one get one free)
> 1 btc to <= 4 btc considered for public sale 1 (total allocation 4000 Chip as buy three get one free)
> 4 btc to <= 7 btc considered for public sale 2 (total allocation 3000 Chip)
Anything above 7 btc will be returned back to the senders who sent it late. Transaction fees will be deducted.