My meter measures it in m³ and my supplier, knowing the exact caloric value of the product they’re selling, tells me in kWh on my bill.

edit: m³ of course not ² lol

In very cold climates, having a hybrid system like the one you’re describing is that universal no brainer in my opinion. Especially since most cold regions also typically have really long transitional periods where your heat pump is most efficient and pays itself off fastest. Combining that with turning it off during harsh winter weeks gives you the best of both worlds.

That’s a perfectly normal number for any home that isn’t very new and perfectly insulated.

My 37sqm appartment needs approximately 5000 kWh in natural gas per year, 876 kWh last December, so 28 kWh per day on average. The building is admittedly old and not perfectly insulated but it’s also not a log cabin out in the open in Finland, but instead a flat enclosed within 3 other flats in the middle of cosy, never below -8C Germany.

21 kWh in a log cabin in Finnland actually seemed pretty low to me. It’s sort of obvious OP is using a heat pump and the cabin must really be absolutely tiny.