I came across this Jetwave battery that uses 12 semi solid cells. Endurance Battery – JetWave Official
That would make building a battery pretty easy and great specs. I think it might be those cells Farasis S55 Semi-Solid NCM Lithium-ion Pouch Cell 3.7V 55Ah 205Wh High Energy Density Battery
12 cells to solder together instead of hundreds. You just have to sort out the case building and maybe add a BMS. The weight sort of checks out!