My current z-wave hub failed. Would a raspberry pi 5 and a (Home Assistant Connect ZWA-2) be all I need to replace my VeraPlus-US gateway?
Skip the Raspberry, go for a mini-PC. More power per dollar (or what ever your currency is). The ZWA-2 will also work good.
I already have a pi 5 running mqtt / node-red. I was hoping to be able to additionally run Home Assistant. Is the ZWA-2 the only additional purchase I need to connect to my Z-Wave devices?
You can, but only if you want to complicate your installation with containers.
There is also the option to run HAOS and then use the addons for MQTT server and Node Red.