You still only need 1 powerful computer. Networks are so fast these days and we have stuff like Tailscale it’s pretty easy to use the laptop as a dumb terminal and do all your work still on the fast computer.
Completely depends on what you're doing. If you're working on GUI software for example, you need to run that on your local machine. This is much easier if you're compiling and running the software on the same machine.
Then there are non-development tasks, like 3D modelling or video editing.
Remote desktop is a kind of solution, but it's extremely sub par. Latency is not good unless you're on the same LAN in my experience.
There's always some latency, but Moonlight has ~5ms latency on my LAN. I average 18ms total latency when I stream to my phone over 5G cell internet, that's with 6ms of decode latency in the phone's (fairly slow) hardware decoder and about 2.5ms encode latency in my AMD RX 6700XT's h.265 encoder.
Then there are non-development tasks, like 3D modelling or video editing.
Remote desktop is a kind of solution, but it's extremely sub par. Latency is not good unless you're on the same LAN in my experience.