Kali isn’t meant to be a desktop OS. Use it only in VM or in a spare rig. It is meant to be a toolbox. So dual boot it with your daily driver OS or use in a VM.

Your Mac can take Linux just well: https://djharper.dev/post/2020/06/07/running-linux-on-my-macbook/

For your 300 bucks budget look nothing else than Thinkpad T480 or HP Dev One. T480 will need replacement batteries if not replaced yet.