joinmarket-clientserver VS sparrow

It's complicated. The more steps you take to obfuscate your transaction, the harder it will be for an adversary to track your coins. You can look into using something like the JoinMarket Wallet to keep your transaction more private.

You can use coinjoin services like joinmarket to anonymize your coins. You can also send them through a lightning swap.

This is a bitcoin service delivered in a low trust manner where the bitcoin user need only utilize software they run and control for the services and can protect themselves from malicious third parties with very little trust or consequence from peers. This is the gold standard of Bitcoin service. Examples include lightning routing, lightning liquidity marketplaces like pool, coinjoins like joinmarket, coinswaps, submarine swaps like loop and others.

If you want to play with OP_CHECKLOCKTIMEVERIFY, you can use the wallet in JoinMarket to create a fidelity bond. Be careful, though, because it's absolutely impossible to spend such a bond until its expiration.

I opened a GitHub issue - https://github.com/JoinMarket-Org/joinmarket-clientserver/issues/1349.

I don't now if it will help you, but the latest SparrowWallet release lists

Exactly this. Blockstream Jade hardware wallet used with Sparrow wallet on a laptop with linux, to make transactions. Then Bluewallet for a watch-only wallet on your phone device.

Its just well established, open source, well featured. While it is a wallet, here it just plays the role of interface. Yes, there are other apps for this, most notably Sparrow.

Sparrow has the best UI/UX in my experience, and it's completely open sourced. https://github.com/sparrowwallet/sparrow