https://hitnmix.com/ripx-daw-pro/
It can even export the separated tracks as midi files. It still has some problems but works very well. Stem separation is now standard in the musical software and almost every DAW provides it.
I find moises (https://moises.ai/) to be easy to use for the tasks I need to do. It allows transposing or time scaling the entire song. It does stem separation and has a simple interface for muting and changing the volume on a per-track basis. It auto-detects the beat and chords.
I'm not affiliated, just a happy nearly-daily user for learning and practicing songs. I boost the original bass part and put everything else at < 10% volume to hear the bass part clearly clearly (which often shows how bad online transcriptions are, even paid ones). Once once I know the part, I mute the bass part and play along with the original song as if I was the bass player.
I wonder why pricing information is so hard to find these days. Would like to get an idea of the same.
It's an up and coming feature that nearly every DAW should have, but most don't yet.
Ableton Live - No
Bigwig - No
Cubase - No
FL - Yes
Logic - Yes
Pro Tools - No
Reason - No
Reaper - No
Studio One - Yes
Mixcraft - Yes
Maschine3 - Yes
https://github.com/samim23/polymath
Polymath is effective at isolating and extracting individual instrument tracks from MP3s. It works very well.