There is a $20+2 at 4pm Eastern time and a $10+1 at 10pm Eastern on Bovada, but those are literally the only two FLO8 tournaments I can find on US facing sites.
And I have found no US facing site that spreads FLO8 as a sit-n-go at all, not even Bovada.
I find that somewhat surprising as, for example, Merge and Bovada offer the following non-NLH sit'n'gos:
It surprises me because Omaha 8 is probably the third most popular type of live tournament (behind NLH and PLO). And although FLO8 is not at all popular outside the US, these are supposed to be the US-facing sites.
Merge has the ability, in the sng lobby, to customize your own sng. Anybody interested in playing FL Hi/Lo should look out for those custom SNG's, and especially become active in creating them, since their limit of one custom sng created per account limits the supply of these sng's to get going. I would love to possibly help start FLo8 tournaments get running. and horse as well. but it requires that YOU get active.