I do not think anybody is hardcore hammering on prebuilts daily. maybe for a week or two when glamping, but not daily hardcorp 90~10~90 cycles.
Most of the off-grid folks were not willing to sink that much coin into that small of capacity so they all went the DIY pack route, those you can find tons of data on. In Australia some folks are approaching 20 years with Winston cells with less than 10% degradation in capacity, matter of fact most are reporting under 5% but those are the plastic or nylon cased Winstons, Sinopoly's and Calb's with only Winston still producing them.
the newer aluminum prismatic cells are all at maybe 9 years of use, about 7 or so of popular use, so the Jury is still out.
It really boils down to how good the cells the prebuilt use's if they are buying the same cells that 50% of the members of this forum bought expect them to be swollen, degraded and worthless in 2-3 years of any use. if they used actual mass produced/bulk purchased EV level cells then I would guess the same as the winstons and the other plastic format cells.