Bitcoin is rather pseudonymous than anything else, because your transactions are entirely public on the Blockchain. Of course, no one can tell who you are by directly looking at addresses and transaction hashes on-chain. Still, it's possible that the government manages to link your identity with an specific transaction or Bitcoin public address. That's because the blockchain ledger is open for anyone to explore at will. With privacy coins like Monero and Grin, it's nearly impossible for anyone to lookup an specific address or transaction hash using a block explorer of their preference. In the case of Monero, for someone to be able to explore all of your transactions you'd need to share your "view key" with that person. Without it, there's no way to tell how many coins you have or which transactions have been sent/received across the Blockchain.
Nonetheless, Bitcoin still enables you to perform private transactions either on-chain or off-chain. You'd need to have some knowledge on the different privacy solutions available within the Bitcoin ecosystem in order to obfuscate transactions from the general public as much as possible. For on-chain transactions, you can use Wasabi Wallet, the Samourai Wallet, or even Bitcoin mixers. Transactions performed in an off-chain manner using the Lightning Network or offline, are private by design. As long as you rely these workarounds, you'll be able to achieve privacy on Bitcoin without having to recur to another cryptocurrency. There's the always the choice of exchanging Bitcoin to a privacy coin like Monero or Grin, if that's not enough for you. Whichever way it is, Bitcoin is as private as you want it to be. Just my thoughts