For servers purchased in bulk by hyperscalers, OpenCompute has done a great job of coordinating owner requirements for hardware and firmware delivered by ODMs and silicon vendors in the server supply chain. Founded by Facebook, OCP built on the pioneering ethos of whitebox servers at early Google Search.
To create a similar organization for clients, one would need to pool enough buying power to influence the supply chain for "PC" (x86/Arm) client devices. OCP bypassed Tier 1 OEMs and worked directly with Taiwan ODMs. This worked because hyperscalers could implement custom firmware and do their own support. The closest existing client vendor might be Framework, which has not yet managed open-source firmware. Plus Clevo (coreboot) OEMs. DMTF [2] might have some interest.
A possible baby step towards open clients would be an OCP reference design for a "privileged access workstation" to access security-sensitive administrator web consoles for hyperscaler clouds. Include both a discrete TPM and an open silicon root of trust (OCP MS Caliptra or Google OpenTitan are both open firmware). AMD OpenSIL has promised OSS client firmware by 2026 and AMD mini-PC boards are everywhere. The building blocks are present for a high-integrity reference client with open firmware, under control of the client-owning cloud customer.
With suitable licensing, anyone from Tier1 PC OEMs or small vendors could create custom derivatives of the OCP reference client IF they retain mandatory core properties like open firmware and open silicon RoT. We could intentionally reboot the accidentally-open IBM PC ecosystem, at least for the small niche of secure cloud administration. If the OCP reference client is successful, it could motivate a new client-focused org for open client hardware.