For the fuzzy search support, I would suggest upvoting this post.
For the associations, you can use the batch read endpoint listed on this page.
Call would look like this:
https://api.hubapi.com/crm/v4/associations/companies/deals/batch/read
json body where companyID would be replaced with an actual ID:
{
"inputs": [
{
"id": "companyID"
},
{
"id": "companyID"
}
]
}