Not sure for the software wallets, I never used one. Definitely no private key available for hardware wallet, just the xpub(s)

Hmm good question; let me check I did verify I can easily recover various mixdepths from my #JoinMarket wallet in Sparrow

Yes, Sparrow does not make that available to the user. If, for some reason, you want to see a private key, you'd have to import the seed elsewhere.