Cordless Men's Grooming Kit, Facial, Head, Nose Hair Trimmer, Li-on Battery, WaterProof - $19.75 after coupon + free shipping with Amazon Prime
Found this hair trimmer and I think it checks out lots of boxes:
- Li-ion battery,
- USB charging
- Plenty of accessories,
- Great reviews.
- Under $20 https://www.amazon.com/dp/B06XDC47Q6