the way the blockchain works, transactions are sequential. so if your first one gets stuck, you can't create new transactions (aka txs) until the first one is finished.
so... my suggestion would be to create a brand new metamask wallet, with a new password and seed phrase, and everything.
then try sending a very small test of ETH to your wallet. see if it arrives. it should get there within 5 minutes, max.
if you succeed, maybe it's best to set aside that first wallet, and wait for the pending transaction to "cancel". if it doesn't, then you need to involve coinbase customer support, which can be awful.
priority number one is getting you into some cheap tokens before they become expensive.