If you are happy with the Realtek chip, why don't you just get a 2.5 Gbps USB dongle? In the EU they sell for 20-30 EUR on Amazon.
I did that for my setup, one of those each for the NAS, my laptop's docking station, and my Elitedesk Mini Linux server. I get more than 2.4 Gbps between each of those with iPerf3 and up to 255 MB/s transfer speed with Windows File Explorer and an SMB drive on the NAS.
Same here; I am considering to pick up a Lenovo Tiny at some point and add a proper low profile PCIE card with a riser card. But as long as I am not using as a router (e.g. with opnSense or pfSense) the performance is good enough for me with the USB dongle.