Can the Max 10 and arria 10 support SSTL1V8 bidirectional differential comms ?

Hi @RFoy0​

Yes, Both device supports bidirectional differential SSTL-18 Class I, II(Refer below image).

For more details refer Device Handbooks

Arria 10: https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/arria-10/a10_handbook.pdf

Max 10: https://faculty-web.msoe.edu/johnsontimoj/Common/FILES/m10_handbook.pdf