Great questions @Leah_Margaret and well done for confirming your first two sits .
No homeowners aren’t checked or verified by THS when they join up .
You could look for sits that have reviews from other sitters rather than New listings with no reviews.
There are lots of solo female sitters on this forum who will willingly share their advice .
Here is an inspirational thread where many solo female travellers have previously shared their advice and travel experiences. https://forum.trustedhousesitters.com/t/solo-woman-travellers