When you said "more or less, or ish?
When you don’t have an exact number.
It will take us 3 hours to get there, more or less. It may take 2 hours and 45 minutes, or it may take 3 hours and 20 minutes. You are unable to be precise.
“ish” is a lot more informal. We should be there 4-ish or so, depending on traffic. You may be there a bit sooner, you may be there a bit later.