Everything @Crabwomansays. The best way to do it would be to get married, he gets a job in the UK with a company that has offices in the US then after a year he can apply for a transfer which makes him eligible for an L1 visa (and you and DD L2s). So childcare maybe not so much of an issue as DD could be school age by the time that happens. What you’re talking about now- his ‘dream’, being unmarried, just applying for jobs there sounds a bit ridiculous tbh.
But since you’ve asked about childcare as in the UK you get good ones and bad ones. Most are people use daycare. You also get in home daycares, I guess comparable to like a childminder, half day preschools used by SAHP and nannies or nanny share.
Varies by state but mostly ratios are much higher so even in good daycare centres it can seem busy and chaotic. I found the cost on par with the UK but some of it was tax deductible. Funded hours aren’t really a thing either, our city apparently did 1 day per week for 4YOs but no idea how that actually worked in practice because we left when DD was 3.
The daycare had no outside space, in fact none of the ones we viewed did, but they went for a daily walk unless it was torrential rain or below 20 Fahrenheit (about -7 🥶) and it was opposite a park and zoo so they went there a lot. Vaccination was mandatory in our state to attend, including chickenpox so you might have to do that. A yearly doctor’s exam, and specific to our area a lead blood test were also required. Ours was all organic food but the actual meals were not very adventurous so a lot of apple sauce, mac and cheese etc. School starts at 5 years old, not 4, so the equivalent to reception is at daycare.
-If this does ever end up happening, you can go tour some places, same as if you were moving within the UK! But it sounds like childcare is the least of your concerns.