I mean fiat shit has a base unit and then you use k$, M$, B$ if you need to deal with big figures or cent for lower figures, which are not even 3 zero below the unit. I don't think it's much better.

My main concern is that 1 sats might not be small enough eventually.

At 100 sats = 1$ you will have 1 sats= 1 cent, then you start losing granularity. Bitcoin above 1M$ (and we will get there eventually) would be an issue with roundup (unless we get there because USD collapse to zero).

Also habing one more digit would be E-9, matching kilo, mega, giga and mili, micro, nano from standard units.

But in the end it's a matter of perspective and habits. Many people have to deal with a local fiat that has similar level of value than a satoshi. It will be no big deal for them. Only some large Northern countries will need to adapt, but history show that people adapt to much more absurdity and inconherance. If this is told as blocking adoption, it's just an excuse.