Tuners that do a low B

[DarkHeart]

The Mooer baby tuner does the low B very well

[Geek99]

Zoom b2 gets it too

[Jazzjames]

No directly related but oerhaps worth a thought: The B can be harder to intonate if you don't play it sympathetically. I found that (like an E on double bass) i had to work to get a clear and defined sound with the B.