Which full node implementation(s) supports SegWit
Bitcoin Core has supported segwit for a long time and will have decent segwit support in the GUI/RPC in version 0.16 which is going to be released hopefully within the next couple of weeks. Knots also supports segwit, as does btcd I believe. Others like bcoin probably do too but I'm not sure, someone else might know better

You can look at this page for some general ideas: https://bitcoincore.org/en/segwit_adoption/