I'm not entirely sure of the laws where you are, but here any support person who is with you can stay with you throughout whatever you're doing. I'm not too sure because I haven't heard of queue skipping (except at theme parks like Disneyland) with disabilities. Where I am, we have pensioner/concession cards that get you discounts on medical expenses (90% of medications are $7 a box and GPs are free or discounted cost) and cheaper transport costs and household expenses.
As for people judging you for not having a visible disability, those people really need to do some research and shut up. I've had a few problems with disabilities with people in public before including a bus driver who denied my mask exemption and screamed at me until I put one on. And when I rang the bus company to complain the customer service woman asked if the colour of my walking stick is to show what disabilities I have because "all blind people have a white cane". No lady my walking stick is pink because I like the colour not because I'm advertising by disability to the world and what about my blind friend with a blue cane? I rang the company later that week and got a manager who insured that both employees would get extensive disability training. If it's an employee of somewhere (e.g. your local supermarket) who is shaming you for using the disability parking spot ask for a manager. If it's a random Karen I'm not entirely sure depending on the Karen. Sometimes with Karen's it's better to walk away and if she follows go into a shop or something and ask someone there for assistance