This is a really odd and potentially interesting idea. NO idea how well it works, but I’m going to dig a bit and see if I can determine the availability. Small loads, but totally off-grid. Looks like it’s really meant for delicates, so probably not a viable thing for your only laundry option.
Looks to be a crowdfunded thing running a little over $160. Yirego.com is the site.
Believe it or not, one of these and a five or six gallon bucket works pretty well for laundry. We have one and use it when camping out in the trailer.
https://www.lehmans.com/p-4444-breathing-hand-washer.aspx
Do you have a spinner or wringer gadget? Hand wringing is a pain. I’ve seen hand spinners that get the bulk of the water out without power.