I'm sorry for your loss.
I was at a funeral last month (colleague) and as far as I can recall the mourners were mostly in dark/subdued clothes, but by no means all in black. I wore a knee length dark grey dress with short sleeves, dark tights, black cardigan, black shoes (warm day).
I don't go to many funerals but my parents do (generational thing) and when I said something to them not long ago about wearing all black they pooh poohed that idea as quite old-fashioned, which surprised me immensely, as they're extremely conservative socially.
My dad would always wear a suit with immaculate white shirt and black or subdued dark tie to a funeral, and smartly polished black shoes, but that's not such a reach for men, is it? If they have a suit at all, they're most of the way there.
My mum would dress fairly smartly but not necessarily in black. Something subdued, so navy/dark green/grey/dark brown, maybe, with a plain white top. She's well up in her 80s and no fashionista, so would never have been likely to wear something short or clingy or lowcut! I'd say those are all no nos at a funeral purely because the focus of attention at the funeral should be the deceased, not the mourners.
I think we're in an uneasy time of having no universally agreed consensus about how to behave when someone dies. In Victorian times there were rigid rules about mourning - what mourning dress to put on, depending on how close you were to the deceased, for how long, and so on. Restrictive, but also helpful to others, as they could see at a glance that you were in mourning, and that it was for someone close and that the death was recent, and as death was so common then people knew how to behave around the bereaved, what to say, what to expect. I'm sure it was often insincere but it's much worse nowadays when people don't know what to say so say nothing.
Nowadays people have far less direct experience of bereavement (fortunately) and as conventions have all gone out of the window we often feel at sea trying to do the right thing.
I'd say respect is the key. Families normally make it clear if they want something unusual, like 'She loved bright colours, please don't come in black' as my grandmother wanted.