I just did this so I have a couple of answers.
The easiest way to do it is with Soundiiz - Transfer playlists and favorites between streaming services
I used the free version a few years back to go between Apple Music and TIDAL, and it was a real chore. If you use the paid version ($4/month or $36/year) it goes much more smoothly and gives far more accurate results.
Here’s the definitive guide: Definitive Guide: How To Copy Favorites and Playlists from Tidal to Qobuz - CA Academy - Audiophile Style
My TIDAL subscription doesn’t run out until later this month, so I can’t say for sure what happens to your TIDAL albums, but I’ve read here on the forum that they disappear. However, they should still be available in your TIDAL account in case you ever renew your subscription.