>but there's no way to get the data into it at 100 Gbps
I'm confident you can get 100 Gbps in by aggregating M4 Mac mini ports.
I resell a $199 Microtik CCR2004-1G-2XS-PCIe SmartNIC with 2 x 25 Gbps QSFP28 that connects to a x8 PCIe 3.0. (I still have a few available for $140 plus shipping plus a few refurbished 16 x 10 Gbps for $400 and 8 x 100 Gbps switches for $800).
Theoretically you can connect that SmartNIC to two of the three M4 Mac mini Thunderbolt 4/USB4 ports that pass through 2 x x4 PCIe 3.0, if you can figure out how to aggregate the two x4 PCIe lanes into a single x8 port. The driver source code is for Linux and could be ported to MacOS. You then aggregate the ports with the 100 Gbps switch.
I'm pretty sure you could create a new PCB design with a larger Broadcom switch chip model to attach to the 10G Ethernet, two 10 Gbps USB-C ports plus the three Thunderbolt 4/USB4 port and write a new driver to aggregate over the 6 ports. You'd have 126 Gbps minus the PCIe overhead and could combine it into a single 100 Gbps QSFP28 port.
I already warned this is still theoretical. Broadcom might not sell you the switch chip, Intel might not sell you the Thunderbolt chip and Apple might block the installation of your device driver code.
But people already proved the interconnect with the Apple Thunderbolt Bridge driver at 3 x 10 Gbps connected via large expensive Thunderbolt hubs [2]. Others just connect each port to different M4 Macs [1][3][4] in various ways.
I know this should all be possible, but isnt really because Apple doesnt care about this use case.
I'll just stick to Orin AGX modules with their proper pcie slot and real Linux support. I want to do something meaningful with the incoming data and not waste years just getting the link up and running.
I'm confident you can get 100 Gbps in by aggregating M4 Mac mini ports.
I resell a $199 Microtik CCR2004-1G-2XS-PCIe SmartNIC with 2 x 25 Gbps QSFP28 that connects to a x8 PCIe 3.0. (I still have a few available for $140 plus shipping plus a few refurbished 16 x 10 Gbps for $400 and 8 x 100 Gbps switches for $800).
Theoretically you can connect that SmartNIC to two of the three M4 Mac mini Thunderbolt 4/USB4 ports that pass through 2 x x4 PCIe 3.0, if you can figure out how to aggregate the two x4 PCIe lanes into a single x8 port. The driver source code is for Linux and could be ported to MacOS. You then aggregate the ports with the 100 Gbps switch.
I'm pretty sure you could create a new PCB design with a larger Broadcom switch chip model to attach to the 10G Ethernet, two 10 Gbps USB-C ports plus the three Thunderbolt 4/USB4 port and write a new driver to aggregate over the 6 ports. You'd have 126 Gbps minus the PCIe overhead and could combine it into a single 100 Gbps QSFP28 port.
I already warned this is still theoretical. Broadcom might not sell you the switch chip, Intel might not sell you the Thunderbolt chip and Apple might block the installation of your device driver code.
But people already proved the interconnect with the Apple Thunderbolt Bridge driver at 3 x 10 Gbps connected via large expensive Thunderbolt hubs [2]. Others just connect each port to different M4 Macs [1][3][4] in various ways.
[1] https://x.com/alexocheema/status/1807882764261417000
[2] https://www.youtube.com/watch?v=GBR6pHZ68Ho
[3] https://www.youtube.com/watch?v=2eNVV0ouBxg
[4] https://www.youtube.com/watch?v=SkmrUWyZThQ