I used SmartThings for years and was hesitant to switch but I was able to control all my devices in ST from HA without moving/repairing/etc devices over. Once I had seen the power of HA I started a _slow_ migration over (took over a year cause I was lazy). The entire time the house worked just fine (except when the internet was down and then only the HA “native” stuff worked).
My biggest recommendations and I wish I could make this text bigger:
Do NOT use a raspberry pi for your HA host. They are unreliable and you will incorrectly blame HA for RPi’s failings (like I did). After moving to a dedicated cheap BeeLink mini PC my HA became rock solid.
You can play around with HA in docker or a VM as well and even host it there indefinitely but avoid RPi’s as your host, you’ll thank me later. If you want dedicated hardware (I do recommend that since smart house stuff often needs to be “always up” and the family doesn’t care/understand why your homelab is down, just that the lights don’t work) then go for a BeeLink or HA’s hardware offerings.