Well, on account there isnt really a working AD or SMB implementation, little printing support, and most NICs arent supported (also: no wireless at all), then I would say there is little attack surface :)
Yip, I remember a virus that hi-jack your bios to draw a flag of some country before every boot; this was in 1998/dos years. You were "sharing" games with your friend they downloaded from geocities... good times. To think a intel ME like vulnerability was already possible back then(if not more) for your bios.
Well, PCs had been suffering from viruses long before they got network adapters...