I've unfortunately had the responsibility for organising 4 funerals over the past 10 years, and my view is that funerals are for those who are left/the living. I know not everyone agrees with this, but I believe once you're dead, you're dead; and there is no afterlife, etc. So, to me, it's more about those who are still there, mourning the person who died. Therefore, I certainly didn't care how anyone turned up, (but my second cousin's wife, who always dresses a bit more revealing, was a source of some speculation!) It was the fact that people turned up, and came to speak to my Mum/sister/friend (the nearest person to the deceased), and shared stories, or talked about what the deceased had meant to them. Those are the things that stick with me.
I've also had to pop out of work for a couple of hours to attend a funeral of a neighbour/extended family member, and have gone in my work clothes. I don't have to wear a uniform, but we're business casual, so I tend to wear darker colours that day, and take a suit jacket to put on. If it was stinking hot, I'd probably wear navy/black linen trousers and a blouse. The one full Catholic Mass funeral I've been to, there were (mainly older) ladies wearing mantillas, but as I'm not Catholic/religious at all, I stayed nearer the back, and stood up/sat down when my friend's Mum did, but didn't go for communion, obviously.
Anyway, what I mean is that, whilst I would do my best to comply with the common understandings of what happens at a funeral, if I didn't then it wasn't meant as a slur in any way. I'm sorry for your loss, OP, and those of others.