Grill/Fireplace inserts for DIY in the US

Hi all! First time poster long timer lurker.

I'm building a fire pit/grill area in the backyard and found some cool designs using an insert surrounded by gabion walls:







Trouble is can only find these inserts and kits for sale in the UK and Europe:
https://www.gabinova.co.uk/gabion-block-fireplace-bbq

I can DIY the gabion part but can't for the life of me find any kind of fireplace/grill inserts like these in the US. Anyone ever seen anything like this?

Thanks!