I don’t know anything about OpenBSD, but this sounds like a driver issue. Have you looked at the OP’s blog link in the OpenBSD on the Framework Laptop thread, specifically the support log section?
Are all the relevant drivers loading at boot - pchgpio, iic, dwiic, ihidev, imt? You might compare your dmesg output with this post from the OpenBSD mailing list. If you have:
ihidev1 at iic2 addr 0x2c gpio 3, vendor 0x93a product 0x274, PIXA3854
somewhere in there, then it’s probably not a touchpad issue and you can move on to other diagonses.