I really had to search to find the output details (which, generally, means the numbers from those details are not the strong point of their product so they hide it):

A very low-end ASIC (S9) consumes 33.6 kWh / day. So the HomeBiogas 2.0 would only run an S9 for about 3 hours per day, even assuming no loss from running that gas through a generator. I don't know the efficiency of a small genset, but let's say a 5 kW Gretech (which I found on Alibaba when doing a search) running at less than full power would have a horrible efficiency. You might see that HomeBiogas 2.0 produce enough gas to run the generator and an S9 for just 1 hour per day. I couldn't even find a smaller capacity genset, though I'm sure they exist.

So, to conclude: bitcoin mining is very energy intensive. While home biogas can have use cases that make sense (e.g., cooking stove use), bitcoin mining is not one of them.