Building a FEN of itself (in 6 steps)

(Dall-e creation)

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Breaking Update — see below after the blue question

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Step #1

r1n1b1q1/k1b1n1r1/p1p1p1p1/1p1p1p1p/1P1P1P1P/P1P1P1P1/K1B1N1R1/R1N1B1Q1/

Step #2 (cut)

r1n1b1q1/

k1b1n1r1/

p1p1p1p1/

1p1p1p1p/

1P1P1P1P/

P1P1P1P1/

K1B1N1R1/

R1N1B1Q1/

Step #3 (spread)

r 1 n 1 b 1 q 1

k 1 b 1 n 1 r 1

p 1 p 1 p 1 p 1

1 p 1 p 1 p 1 p

1 P 1 P 1 P 1 P

P 1 P 1 P 1 P 1

K 1 B 1 N 1 R 1

R 1 N 1 B 1 Q 1

Step #4 (place a chessboard in the background)

Step #5 (replace letters with corresponding figures)

Step #6 (clear all numbers)

The FEN of the above diagram is:

r1n1b1q1/k1b1n1r1/p1p1p1p1/1p1p1p1p/1P1P1P1P/P1P1P1P1/K1B1N1R1/R1N1B1Q1/

...which is precisely the step #1.

Question

What is the minimum number of moves it takes to produce a (legal) FEN of itself from the starting position in an orthodox chess game?

(23 full moves are needed to reach the above position)

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Next day update

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After a remark by two virtual friends of mine on France Échecs, I have to admit those 6 steps are a bit difficult to understand – they also open the door to a "zero solution": just apply the 6 steps to the opening position and voilà... the end FEN is the same as the starting one! Silly me!

Forget the above 6 steps and answer those (much simpler and 100% equivalent) questions:

(Qa) Find the shortest orthodox chess game leading to a legal FEN where there are 32 digits "1" present in the FEN 

[a solution after Black's 10th move is spoiled under the second Dall-e creation].

(Qb) Find the shortest orthodox chess game leading to a legal FEN where there are 24 digits "2" present in the FEN

[a solution after Black's 17th move is spoiled under the (Qa) solution].

(Qc) Find the shortest orthodox chess game leading to a legal FEN where there are 16 digits "3" present in the FEN.

(Qd/e/f/g) Find the shortest orthodox chess game leading to a legal FEN where there are 8 digits 4/5/6/7 present in the FEN.

(Qh) Find the shortest orthodox chess game leading to a legal FEN where there are 7 digits "8" present in the FEN.

(Qi) Find the shortest orthodox chess game leading to a legal FEN where the numbers 1 to 8 are present in the FEN.

More variants are possible, on this theme, of course (prime numbers, Fibonacci numbers, square numbers, etc. – but enough for today, let me have a light petit-déjeuner !-)

(Dall-e creation)

ANSWER to (Qa) : the position hereunder is reached after Black's 10th move.

There are 32 digits "1" in the corresponding FEN:

r1b1k1r1/1p1n1p1p/1q1p1n1b/p1p1p1p1/P1P1P1P1/1Q1P1N1B/1P1N1P1P/R1B1K1R1

ANSWER to (Qb) : the position hereunder is reached after Black's 17th move.

There are 24 digits "2" in the corresponding FEN:

2b2k2/2p2p2/2n2n2/2p2q2/2P2Q2/2N2N2/2P2P2/2B2K2

The above position was achieved with Black mirroring White's every move:

1.e4 e5 2.Qh5 Qh4 3.Qxh Qxh 4.Qxg Qxg 5.QxR QxR 6.a3 a6 7.Bxa Bxa 8.Bxb Bxb 9.BxR BxR 10.Bc6 Bc3 11.dxB dxB 12.d4 d5 13.Nd3 Nd6 14.Kf1 Kf8 15.Qxe Qxe 16.Qf4 Qf5 17.Nf3 Nf6

ANSWER to (Qc) : the position hereunder is reached after Black's 17th move.

There are 16 digits "3" in the corresponding FEN:

r3k3/p3b3/n3b3/Q3p3/q3P3/N3B3/P3B3/R3K3

The above position was achieved with Black mirroring White's every move:

1.e4 e5 2.h4 h5 3.Qxh Qxh 4.QxR QxR 5.QxN QxN 6.Qxg Qxg 7.f3 f6 8.d4 d5 9.Qxc Qxc 10. Qxb Qxb 11.dxe dxe 12.fxe fxe 13.Fe2 Fe7 14. Fe3 Fe6 15.Qd5 Qd4 16.Na3 Na6 17.Qa5 Qa6