Logic Masters Deutschland e.V.

Previous Dutch Flat Mate Puzzles
This has been a weekly series since '18 Oct 23'. Here is a spreadsheet link for all the previous puzzles in the series, which also has a few teasers for upcoming constraints/guest setters in the series (subject to change).
This alternative link offers a limited LMD search for Dutch Flat Mates.

Special Thanks
This puzzle was a collab with sujoyku, who suggested a constraint called "Sum to 9" for the series, we then independently came to the idea that using N, rather than 9 would be more interesting and this puzzle is the result.

Last Friday I released an N's Neighbour Sums puzzle with no Flat Mates —that was released without issue and if anyone tells you otherwise... then please tell them that I once again apologise profusely for the missing given on the sudokupad link— that you can play here: N's Neighbour Sums

To play the puzzle, please click the image:

Initial Setter Difficulty: 3 / 5

Normal Sudoku rules apply
Place the digits 1-9 so that they do not repeat in any row, column, or 3x3 box.

Dutch Flats
Every 5 in the grid must have a '1' directly above it or a '9' directly below it. It may have both, but it doesn't need both.

N's Neighbour Sums
A clue outside the grid at Row N/Column N indicates the sum of all digits that are orthgonally adjacent to N (the row/col number) in that respective row or column.
For example, if Row 3 reads 246835791 then the N's Neighbour Sum clue would be 13=8+5.

Hint to start

The single digit 2 clues are doing good work when combined with C2 and happy 5s. C1 then has a surprisingly amount of tension.

Visual Example (4x4):
Fortunately there are no sad 5s in this example
In Row 1, N is 1, and the digits next to N are 3 and 4.
3 + 4 = 7.

Next Week
We welcome back Jobo as guest setter, and I'm certain it's with more than the 'Minimum' effort!