/tS/ is quite a different story due to it being an affricative.
Onset: shm. Nucleus: o. Coda: d. One syllable.
The trick is one continuous motion of pursing your lips, closing and then opening your mouth as you roll the constants together.
I wonder if the grandparent is French, because I would never have considered to pronounce chmod like this. Then again, I say C H mod and C H own, which apparently isn't the standard pronunciation, so what do I know!
I think what I’ve learned today is that no one pronounces any of these words even remotely the same!
...and while we’re at it, let’s do “char.”
https://en.wikipedia.org/wiki/Phonotactics#English_phonotact...
https://en.wikipedia.org/wiki/English_phonology#Phonotactics
/ʃm/ is not a legal onset in native English. (Let alone /tʃm/, which is how I pronounce "chmod" - two syllables, /tʃə 'mɔːd/.)
"Schmear" is a Yiddish loanword coming from German, where /ʃm/ is perfectly legal. So it's pronounceable by the human mouth, it's just a little awkward for English speakers.
/sm/ and /ʃr/ are both legal in English, so you might think of it as something like those. Can you pronounce "smear" or "shrine" as one syllable?
(I'm not sure /tʃm/ is valid in any language - words or names that start with "chm" seem to be Polish/Russian words transliterating /xm/.)
Oh it sure is in Croatian (and other Slavic languages), "tʃ" is written as "č". We even have slang words like "čmr-lji-ti" [t͡ʃmrʎiti]. "r" (rolling r) can function as a vowel.
The Dutch word “striktst” is of course also pronounced exactly how it's spelled, and in one syllable.
https://en.wikipedia.org/wiki/Swedish_phonology#Phonotactics
On-topic, I pronounce chmod as one syllable with "sh", like schmuck.