Rainbows aren't reserved for gay people.
Wear as many rainbow kilts as you want - they're lovely and beautiful and supportive. Just be prepared for people assuming your gay. XD
My only note about rainbow capitalism - it's nice to show support in public, but largely meaningless if the company isn't contributing to the community somehow. Examples might include hiring and giving promotions to lgbtq, using lgbtq designers, donating a percentage to charities, sponsoring PRIDE events, etc. Plenty of companies produce pride stuff just to make money. I've seen some places that are happy to produce pride items and put them right alongside confederate flags and nazi dogwhistle designs and the like, so I'd take care if that matters to you.
It's also OK to get something just because you want it for yourself to show your support. But something to think about.

My only note about rainbow capitalism - it's nice to show support in public, but largely meaningless if the company isn't contributing to the community somehow. Examples might include hiring and giving promotions to lgbtq, using lgbtq designers, donating a percentage to charities, sponsoring PRIDE events, etc. Plenty of companies produce pride stuff just to make money. I've seen some places that are happy to produce pride items and put them right alongside confederate flags and nazi dogwhistle designs and the like, so I'd take care if that matters to you.
It's also OK to get something just because you want it for yourself to show your support. But something to think about.