This is a classic neon sign from the early 30ties, adorning a central wall in Stockholm, Sweden. As @Scott points out above (I am merely trying to summarise) is that neon sign - particularly that old - tend not to conform to font faces. They are subject to practical problems, back then is was the literal bending of glass tubes. A difficult and at times dangerous job.
What is worth noting is that the letters do seem more engineered than designed, and this is the case: constructed. The kerning is a little odd, the R looks a little unbalanced. As the OP points out, it is a creative way of constructing ö, and it is likely that this is primarily for practical reasons.
So. It is not a font as such, it is a construction.