We kind of had some of that experience because our public online/blended program was pretty much a part time job. The overall requirements were so low that we just expanded and added extra things...
After starting part time homeschooling and seeing what it does I am convinced that it is the way to go for gifted kids ... I was in a Montessori environment and it worked out but a regular school can only accommodate so much.
A year at home and he breezed through 3 years of curriculum in 9 months - and he found it rather easy and relaxing because he worked at the most 3 hours a day.
It is a joy to teach a curious mind - and we have done quite a bit on the side - from documentaries, to museums to research and ... yard work, cooking, experimenting.
And because there are no peers sitting next to us who would judge my son for actually enjoying to learn and explore - the attitude towards learning in general has changed ... a difficult math problem went from being a "problem" to "fun challenge". And suddenly my child writes pages of essays and stories... voluntarily because ... no hurry and no pressure ... I think the 2 hours for " state standard" schooling is very realistic - a bit more depending on how much writing there is but plenty of time for extras for sure. Many parents of gifted children aim for early graduation ... I personally would rather like to see my son go broad and get extra knowledge in other areas- non school subjects, or deeper understanding, than race through the state curriculum and join college early. There is so much to learn to keep a curious mind busy!