FWD HAR-1 trucks. Actually when you start looking, they seem to appear in a lot of Dutch liberation pictures. It seems there was a unit moving around the country pulling smoke generator trailers.
Picture1 Haarlem source:
https://noord-hollandsarchief.nl/
Picture2 Bloemendaal source:
https://noord-hollandsarchief.nl/
Picture3 Amsterdam source:
https://beeldbankwo2.nl/
Picture4 Apeldoorn source:
https://beeldbankwo2.nl/
Picture5 Zutphen source:
https://beeldbankwo2.nl/