design ≠ 'made'. If someone is 'put the things together' then that is more about 'making' than 'designing'. TSMC absolutely manufacturers (makes) A17 chip dies.
There is decent chance that Apple has modified a Samsung design so that it tweaked toward Apple's preferences. Can't really 100% decoupled the design from the fab (manufacture) process. If Apple has selected Samsung Fabs they have been looped into the design process along to way to some extent.
P.S. from the first article in the thread
" ... his manufacturing process has not previously been deployed at a commercial scale. Sources familiar with the matter said that the sensors are to be supplied by Samsung's System LSI division and mass-produced by its foundry division. ..."
Samsung System LSI division is the 'logic design' part of Samsung. Typically works closely with the Foundry division (which produces the wafers with the chip dies on them). If this is being 'supplied' by Samsung then likely hand some contribution to the design. Otherwise Apple would only be talking to the foundry division.
2024
https://petapixel.com/2024/02/14/canon-patents-a-triple-layer-high-speed-stacked-image-sensor/
earlier 2025
https://petapixel.com/2025/07/30/sonys-triple-layer-image-sensor-promises-huge-performance-gains/
( and Sony has discussed this general concept in previous years. This 2025 is more demo of 'product' than working on the concept. )
pretty
from ealier in 2025
it isn't like Apple doing a 'thiple layer' design is revolutionary. Several sensor maker/consumers are doing them. Apple's will have some specific points they want to focus on, but the general notion that Samsung is no clue about design and Apple is telling them everything they need to do is likely overblown.