Some of the rackmount kits for previous generations already reroute the power button and connectors to the front, like this https://racknex.com/wp-content/uploads/2023/04/with-power-bu.... (Though why not just install it backwards?) I guess they will be able to run a little lever under the M4 model the same way.

Actually, the M4 model is a little taller so it no longer fits in a 1U rack mount. Whereas before you could fit 2 horizontally in 1U, now you'd possibly fit 8 or 9 vertically in 3U. (Edit: This company says 10 per 2U https://www.racksolutions.com/m4-mac-mini-apple-hypershelf.h....)