Dedicated FN row supported by 2 out of 5 links above, check Cyboard and MoErgo. Most places (all in these links) provide turnkey, no soldering required. Agree

Dedicated FN row supported by 2 out of 5 links above, check Cyboard and MoErgo. Most places (all in these links) provide turnkey, no soldering required. Agree your requirements get into rarefied territory if you want something ready-to-go, split, programmable, with FN row. But there are options.