The Unitree Go1 seems the most promising among the affordable ones.

https://www.unitree.com/en/go1

https://www.youtube.com/watch?v=xdfmhWQyp_8

Would you know whether it’s feasible for hobbyists to make one of these at home by assembling components

Probably, but not at the price point of $2700.

It would probably be $25k-$50k and 1-3 years of development time depending on your skill set.

If you're interested in making one by yourself, you should check out Josh Piper[1]

[1] https://jpieper.com/2020/11/09/mjbots-november-2020-update/

Kind of, see: https://odri.discourse.group/

It is indeed pricey though, IIRC the cost of a Boston Dynamics Spot-like robot came down to around $6-7k. There is still room to drive the price down though.

The ones they used are Robotis OP3, a snip at $14,199 each (https://news.ycombinator.com/item?id=35812475)

Bunch of servos in human shapes is not too expensive, available from about $1000-1500.

I'd recommend XGO-mini2. It just finished it's Kickstarter funding for the version 2, which runs on raspberry pi. (disclaimer, I did contribute to their Kickstarter) and optionally also comes with an arm.