If I was to sell devices that had a 433MHz transciever for them, to communicate with cheap smart home gadgets, does that require any sort of certification or license?

Likewise, if I was to import e.g. PIR sensors with 433MHz transmitters in them, is there some process that you're supposed to go through to check they're compliant before selling them?  If so, I wonder if the people I bought my alarm from bothered doing so...

Or is it open season within the GURL limits?