for X86 i am using some OpenWRT supported Mellanox Connect X3 cards
I also have a Dual Port QSFP+ (For 10GbE needs QSFP to SFP adapter)
Your can get them in various form factors
https://www.ebay.ie/itm/162990180516?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649
https://www.ebay.com/itm/233621305252?hash=item3664ea37a4:g:LzsAAOSwb65e8sb3