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I guess if you only need two more pins this would be okay, but in general, this sounds like a job for an I/O expander chip?

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From the Reddit thread the article is based on, OP says:

> I want to run an unmodified QMK firmware so I can keep up with updates without having to continually merge my changes into HEAD, and in my research with IO expanders I would have to rewrite the matrix scanning code.

QMK supports a “custom matrix” option which makes using an IO expander or demux extremely easy. We use them for the NIBBLE keyboard. The API is stable and keeping changes in the working tree would be fine. It’s more likely the keymap would break at some point for some reason other than the matrix driver.

Yup. IO expander chips are the real deal. Having good knowledge on them would enable you to extract a lot of value from even the tiniest of micro controllers.

Especially ones tht have an SPI or an I2C interface.

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