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Summary
Great hardware, poor software – that’s the Sofirn SK31 in a nutshell. The combination of a powerful LMP LHP73B with a well-regulated driver, a two-stage tail switch, a separate switch for the lockout and a screwed cover for the USB-C charging port provide the perfect hardware foundation for a great flashlight.
The operation is all the more disappointing. The two-stage switch leaves much of its potential unused. For example, there is no direct access to the lowest or highest brightness level and in Tactical Mode, the switch must be held halfway down for a full five seconds to keep the flashlight on. Minor firmware bugs make the overall experience even less enjoyable.
The full review is available here:
English review at BudgetLightForum
German review on my website
I have a broadly similar sized pocket flashlight.
It has a single button, a few different modes for basically different numbers of clicks.
Sure, you can call that software, or firmware, or maybe its just a fixed logic gate setup... but the thing doesn't have a usb port. It doesn't need 'updates', it doesn't have an app... to hack it, you'd have to disassemble it and presumably hard-mod it, manually create your own contacts/interface.
It just uses AA batteries... and you can get a set of rechargeable AA batteries, and a charger.