A friend of mine recently died (suicide unfortunately). He was 30 years older than me (in his 70s) but we got on very well, met several times a week, he knew my family and did work for them (was a very good, very skilled 'handyman'). Known him over ten years.
He didn't want a funeral, but there's a 'send off' in the local pub for him soon, planned by his family who I have never met, who'll all be there.
Given he didn't want any sort of funeral, I doubt he'd want people in black/formal attire but I don't want to wear my usual, casual 'few drinks in the pub' clothes either. He would always comment if we met and I was wearing black, saying how I looked a lot better in brighter colours (probably true) so I feel I should honour that somehow. I am also mindful that as he was very popular the pub will likely be very busy and I won't get to sit down, so high heels might not be a good idea either.