#2: Sudoku-Slitherlink hybrids

I'm a big fan of loop genres, and even more so when they are neatly combined with other rulesets. If one tries to combine Slitherlink with Sudoku, it's natural to treat digits as clues, but numbers 4 and larger quickly break the Slitherlink. Here's a pair of my attempts to make it work: a 4x4 that ignores the 4s, and a 6x6 with a "sheep and wolves" mechanic.

Make-A-Snake!

This one is small enough to brute-force, but it's interesting to look for a purely logical path.

Rules:

Classic 4x4 Sudoku rules apply.

Slitherlink: Draw a single non-intersecting, non-self-touching loop along some cell edges. Clue in a cell indicates the number of adjacent loop segments.

All digits 1, 2 and 3 are Slitherlink clues (4s are not).

Difficulty (select to make visible): ★⯨☆☆☆

Solve in Penpa+ (automatic answer check for both numbers and loop edges)

Nehebkau, the First Protector

(Don't ask me about the name)

Rules:

Classic 6x6 Sudoku rules apply.

Slitherlink: Draw a single non-intersecting, non-self-touching loop along some cell edges. Clue in a cell indicates the number of adjacent loop segments.

All digits 1, 2 and 3 are Slitherlink clues (4, 5 and 6 are not).

All digits 4 must be inside the loop.

All digits 5 must be outside the loop.

(Digits 6 don't do anything special)

Difficulty (select to make visible): ★★★☆☆

Solve in Penpa+ (automatic answer check for both numbers and loop edges)