How about the x2 or Alveo series from Xilinx? It is basically the original definer of smartnic.

It comes from solarflare who have a long pedigree of low-latency smartnics. They used to supply Cloudflare, and also supply like 50% of fintechs/financial markets.

You can also just use openonload to accelerate your programs. In this case just doing straight linux socket programming, which can be accelerated without dpdk. Or just use the open source linux net driver if necessary.

https://github.com/Xilinx-CNS/onload

I recommend Intel for 100GbE stuff. Intel's heritage of proper open source drivers (written by their own staff, in house) for FreeBSD and Linux goes back really far.

You could look at the man pages for their very expensive 10GbE server NICs in 2003-2004 and see the @intel.com email addresess of the persons who wrote them.