Started out with XM on a refurbished Palm ($99USD) but I wouldn’t trust it for more than 90 minutes outdoors (gets ~2 hrs indoors).
With a sizeable battery pack (6000mAh) connected it’s currently my long ride choice with EBC.
See: Hammerhead Karoo 2 - General - Xert Community Forum (xertonline.com)
Otherwise I have a KKM2 for most fair weather rides.
I prefer a smaller screen but if I had to start over this 5" screen phone (also $99USD) looks impressive spec-wise (rugged and waterproof) but I have no experience with the brand (reviews are mixed but may be fine as a dedicated BC) –
4000mAh 8MP Camera Rugged Phone Ulefone Armor X6 with Quad-core Processor 2GB+16GB