As of right now, you cannot buy CHZ on Coinbase. However, this may change in the future as the exchange has been known to add new coins from time to time.
NOTE: This warning note is to advise that Coinbase does not currently offer CHZ as a cryptocurrency for purchase. Before attempting to buy any cryptocurrency, it is important to research and verify that the exchange or platform offers the desired currency. Due to the volatility of crypto markets, Coinbase may offer CHZ in the future, but this cannot be guaranteed. Attempting to buy CHZ on Coinbase may result in financial loss or other risks.
If you are interested in purchasing CHZ, you may want to check back on Coinbase periodically to see if the option becomes available.
At the moment, there are a few other exchanges that do offer CHZ trading, so if you are set on purchasing some of the tokens, you may want to look into those options. Overall, it is unclear as to whether or not Coinbase will eventually add CHZ trading, but it is certainly something that could happen down the line.