Sure, again, if a "ballpark" estimate is all you need, voltage might be "good enough", for your needs.
But variance will be very wide, you cannot get a good reading if the bank is under load or charging, an "at rest" measure can take many hours, depends on the chemistry, need 24-72hrs for accuracy.
All this still holds no matter how accurate your voltage reading, the point is that voltage only corresponds **very roughly** to SoC% at the best of times.
So, yes you can build a [voltage - SoC%] correspondence table, but it will only be good for **your** bank, at a given temperature range, and at this stage if its wear cycle, maybe 6mo or a year.
and you will need an accurate SoC meter to build and verify that table.