Personally, I believe you are over-thinking the whole thing.
I have an ESTA and the name on it does not match the entire name on my passport. I have had no problems entering the USA with this ESTA.
Say my name is Mary Jane Jones (not my real name, just an example). Mary Jane Jones is the name on my passport.
On my ESTA application, I put "Mary" as my first name, and "Jones" as my last name - no middle name, as instructed on the web site.
So, my passport says Mary Jane Jones and my ESTA printout says Mary Jones, and that has not caused any problems.
In you case, your passport will say Johan Smith Anderson, and your ESTA could say Johan Anderson, and this should not not cause you any problem.
It doesn't matter to the official who looks at your documentation that, in Scandinavia, "Smith" is also considered to be part of your first name. It is written as a separate word and in the USA it will be considered to be your middle name.
It's the US official who has to be satisfied in this instance, and not your own national custom. So,
go by the US rules on this, and put Johan as your first name and Anderson as your last name. Don't include Smith.
Of course, you could probably still put "Johan Smith" as your first name, and still not have any problems!
