Welcome!
Sorry to hear you and your DC have had such a challenging few years with schooling. Unfortunately, this is not an unusual story for children with his cognitive profile. You will certainly find a lot of sympathy here.
Others will contribute soon, I am sure, but I'll start you off with a few not-necessarily-connected thoughts:
1. It is likely that he will need changes in the approach to managing his educational needs multiple times during his K-12 years. The downside to this is that, even if you find a good solution for one year (or quarter, or month), it probably won't last. The upside is that any approach you try can be treated with a little less emotional investment, as an experiment or trial, just for the time being, or until it becomes evident that it has run its course.
2. It sounds like the concerns with homeschooling were the loss of G&T.com, and the absence of peer social interactions. Those can be addressed. There are many other online or paper curricula available for homeschooling (many of them are discussed in the Recommended Resources room of this forum), some of which have received even better reports than fka EPGY. Many communities have homeschool meetups, coops, partial homeschooling arrangements with public or private schools, etc. Many (or most) extracurriculars do not require enrollment in a specific school, such as recreational sports leagues, library-run robotics clubs, dance, music, or theater.
There is also the point that a child who is currently extremely unhappy and struggling with school is unlikely to be truly benefiting from the peer social contact he receives, since that's a relatively small percentage of the day, while work on skills far below his zone of proximal development is a fairly substantial percentage of his day.
...Just to reassure you that homeschooling may still be on the table, even though your brief attempt didn't work out as expected.
