Mini-ITX Seaberry adds 11 PCIe slots to a Raspberry Pi | Jeff Geerling
Skylake-based Nano-ITX SBC offers 4x GbE and stackable PCIe
Mini Pcie Pcie 1 To 3 Pci Slot Riser Card Mini Itx To External 3 Pci-e Slot Adapter Pcie Port Multiplier Card For Motherboard - Pc Hardware Cables & Adapters - AliExpress
Lian Li Q58 Mini-ITX Case with PCIe 4.0 Riser Card (White) Q58W4
Amazon.com: ASUS ROG Strix X570-I Gaming, X570 Mini-ITX Gaming Motherboard, AMD Ryzen 3000 with PCIe 4.0, WiFi 6 (802.11ax), Intel Gigabit Ethernet, SATA 6Gb/s : Electronics
iTXL-Q47EA - Thin Mini-ITX Motherboard - Global American
GIGABYTE H610I DDR4 (H610/ Intel LGA 1700/ Mini-ITX/ DDR4/ Single M.2/ PCIe 4.0/ USB 3.2 Gen1/ Intel GbE LAN Chip/ Motherboard) - PC Maestro