That Alpkit bag does not look all that stable to me, get the feeling it'd do a fair amount of flopping around off-road.
Using two zip ties or thinner straps would be an option: one below and one above the stem. Should be as secure, if not more secure, than a single large strap.
I've not got any point of comparison, but the medium fuel pod doesn't seem particularly floppy to me. I use it on my 29er, as described above, and on my gravel bike with velcro below the stem. Normal cargo is tube, pump, wallet, phone, keys, gels.
That Alpkit bag does not look all that stable to me, get the feeling it'd do a fair amount of flopping around off-road.
Using two zip ties or thinner straps would be an option: one below and one above the stem. Should be as secure, if not more secure, than a single large strap.