I guess people here will be familiar with the benefits of Sodium over lithium for home power applications.
Given the cells are more available now, eg https://vi.aliexpress.com/w/wholesale-sodium-ion.html
Are any of your existing chargers suitable for Sodium?
A product similar to this GOKKCL Portable Car Jump Starter 80WH Sodium Ion Battery Power Bank 100C Discharge 12V Starting Device Petrol Diesel Car Booster - AliExpress 44 but with solar input might be good for rural electrification?