For silent practice and lonely business hotel nights I always have a Tascam GT-R1 in my gigbag or case. They are sadly no longer in production. I had to repair it numerous times and also had it repaired twice before warranty expired, but this is still the best €€€ I've yet spent on music gear. Poor build quality is a problem sadly, but the features are so good. If I carry around a bass plus case/bag, I don't really mind the cable tbh... I have a short one, about 1m. Long enough so I can see the display while playing.
This little thing uses standard SD cards, you can play all mp3 and wav and some other formats on it. You can slow the playalong tracks down, you can create loops to practise hard sections, you can even overdub playalong tracks... then later hear what you played. This was truly enlightening

"It all felt so good while playing, how can it sound so untight?!" definitely changed my playing. Yeah, you can also have that with a DAW and a computer, and a sound interface etc, but this is so much easier. I have created most of my basslines for my bands using this little helper.
The GT-R1 also has effects and amp sims built in, but they are rather meh. The Ampeg SVT simulation is actually pretty good. While it sound like poo played solo, played to a rock song it really shines. It sounds like many 90's grunge or rock bass tones, compressed and thick.
It also has a good drum machine built in with dozens of different beats to play to. You can of course also use drum tracks as mp3...
And then it has that feature to erase the bass parts of a song, leaving a gaping hole in the upper bass and lower mid register of the song. On some songs you can't hear the bass drum pulse any more, but on most it's still feel- and audible. Very nice if you don't have a proper playalong track.
Speaking of playalong tracks, you guys all know this channel?
MrHITCHER65
He has tons of tracks, original recordings, without the bass part.