What is classed as a 'safe' soft toy for children 7 months and older when introducing into their sleeping environment?

Red Nose does not recommend or promote specific brand name products.

I don’t think it is possible to classify a “safe” soft toy or comforter.
The best advice would be a soft toy that is not too large (risk to baby of suffocation) or too small (risk of choking)
Also, best to avoid any soft toy that has small parts that may become loose or break off (risk of choking)
Red Nose has the following information.
There have been cases of asphyxia in cots cluttered with soft toys and where an infant has slipped out of the sleeping environment onto toys and clothes placed near to the cot.
Small toys, toy parts and toys on strings are a major cause of asphyxial fatalities caused by accidental suffocation and strangulation in babies and choking episodes in young children.
Toys which are hung across the cot should be removed once the child can push on hands and knees or is 5 months of age; whichever comes earliest
https://rednose.org.au/article/soft-toys-in-the-cot

Product Safety Australia also has some helpful information
https://www.productsafety.gov.au/products/babies-kids/toys/stuffed-toys