listing requirements are likely similar (conceptually) to a stock exchange....it’s not really a perfectly open marketplace, but....an exchange which gives some cred to a project listed there
doge seems to be a different animal
Listing requirements are a bit opaque at Coinbase (though likely better than the “pay to play” deals that are common for listings on other exchanges), but as a “serious” exchange they’ve been slow to adopt Dogecoin. I expect that to change at some point, they are just missing out on too much in fees by not carrying it.
Studies have shown that getting a listing announcement on Coinbase brings a major pump to most coins, so having this in dogecoins’ future is potentially bullish for it.