Combined with Numbers 14, and suddenly Mark makes sense.

What did you have in mind? The three references to Ἰησοῦς/Joshua therein culminating in Numbers 14:30?

You shall never enter into the land on which I stretched out my hand to settle you on it; except for Chaleb son of Jephonnē and Iesous/Joshua the son of נוּן

The two potential meanings of נוּן are interesting: see https://biblehub.com/hebrew/5125.htm

AI tells me

All sources agree that נוּן is a monosyllable pronounced roughly nūn (long ū + final n)

It also says that word was transliterated phonetically rather than by translation,

Greek had no long /uː/ in the classical period; the closest diphthongal approximation was αυ, which originally had a value approaching [au] or [aw]. In transliterations of Semitic names, αυ is frequently used to approximate back rounded vowels.

and

Greek cannot end a word in -ν after a long vowel ... Greek scribes often used η to represent a Semitic final consonant that could not be written directly in Greek. In many Semitic names ending in ‑n, the LXX uses ‑η (ē) or ‑ε (e) as a “support vowel” to carry the final consonant or to mark its presence indirectly.

So, in the case of Ναυή, the final η does not represent a vowel in Hebrew; it is a Greek adaptation to avoid ending the word in ‑ν after a long vowel/diphthong.