We like the Fit Warm Apparel long john type onesies. You can get them on Amazon. I can't seem to attach pictures (new android user) so I'm including links to Kaji's instagram.
https://www.instagram.com/p/BfhaJmAF...d=aj8cr6xvzptr https://www.instagram.com/p/BSmmBG3F...=17kxaxvt1ofrm
Last one:
https://www.instagram.com/p/BavO1ZIl...=1cq92izv20dgt
The last 2 pics and videos were from a trip to Toronto. Us SoCal people need insulation when dealing with real cold. Kaji wore the onesie on a cold day, then we layered a puffer jacket after it snowed overnight. He was happy a comfy, warm boy.