Personally I am at the point of thinking that no one should be required to provide services to anyone they choose not to work with.
No one.
No special classes or cases.
No one.
Yes ... services and/or mixed part-service part-product sales, but not pre-made off-the-shelf products.
I also think some standard services can’t be denied. For example, a tow truck driver can’t leave someone on the side of the road because he’s seen kissing his boyfriend when the truck arrives.
So my line would be services that would somehow force the seller into an implied endorcement of a lifestyle choice - which would include a religion or a sexual preference or gender identity (no, they’re not “born that way”), such as a wedding cake maker or wedding photographer,