There's the compute module...32GB of eMMC is an option.

https://www.raspberrypi.org/products/compute-module-4/?varia...

And in some good news on that front, the eMMC storage on the CM4 is twice as fast in many cases as older generations of Pi CMs, as it uses the full 8 bit eMMC bus. It's finally faster (for random IO at least) than any microSD card I've tested.

We've had good success with making SD cards read-only. Of course this means that any data needs to be sent to a service for saving... YMMV.

+1 to this. I've seen this done as well, and it works marvelously. SD cards last half of forever if all you're using them for is a boot device.

It depends on what you are needing to optimize for, industrial use is a very broad category. If you’re caring about the SD card’s endurance for reads/writes, I recommend trying the “high endurance SD” cards. I’ve had good luck with them having continual read/write activity over long periods. If however your concern is mechanical failure due to vibration, stay away from the SD card entirely. Pretty much guaranteed it’ll fail if it’s a high mechanical stress scenario. You’ve got two good options there I can vouch for, use a Compute Module w/ hard soldered eMMC or boot from USB instead. The compute module route is the best in my opinion, but doesn’t always fit the needs, and for those that don’t I recommend USB booting.

Even though you cant "boot" from a PCIe SSD or SATA disk (yet) you can simply stick the boot partition on the sd/emmc and then pull root from the pci attached disk. Kernel might load a little slow but user space should load quite fast.

If the system can see the PCIe SSD, you could always boot off the microSD card but use the PCIe SSD as the primary storage device. Definitely worth testing imo.

There are MicroSD to CD card adapters out there. A bit clunky but they allow you to use full sized SD cards, which might be more durable