Everything out of the box from mainstream sources? Perhaps a little too optimistic for ARM/RK3399 boards.
5.3.y + few patches and correct config or this simple command:
./compile.sh BOARD=rockpro64 BRANCH=current RELEASE=buster BUILD_MINIMAL=yes BUILD_DESKTOP=no KERNEL_ONLY=no KERNEL_CONFIGURE=yes
and here it works as you wanted. dpkg -i *.deb + reboot
00:00.0 PCI bridge: Fuzhou Rockchip Electronics Co., Ltd RK3399 PCI Express Root Port
01:00.0 Ethernet controller: Aquantia Corp. AQC107 NBase-T/IEEE 802.3bz Ethernet Controller [AQtion] (rev 02)
I don’t have possibility to check on Rockpi4 at this moment, but I assume PCI works unless there is some error in the DT.
Edit: I have to note that I didn’t use master build branch so this command above will not work on standard. But on development. This whole stuff is there and troubles are expected.