Wanted: Write-Once MicroSD Card !

Allegedly these exist! — though I have only been able to find them offered for sale by the railroad car.
For certain applications, nothing else will really suffice.
If any of my readers know of (or wish to become) a vendor offering, in (for starters) mid-three-digit quantities:

a) One Time Programmable MicroSD card
b) MicroSD card with a true [...]

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