How to left align dollar sign and right align the number, like Excel currency format?
$ 3,546 $ 44,345
Also, is there a way to create a custom format?
Not possible. (By the way, in Excel it is called Accounting format, Currency is different.)
Yes. Format > Number > More Formats > Custom number format...
More details here: https://support.google.com/docs/answer/56470?rd=1