I am an engineer in a field that has been using >100VDC relays for a hundred years. There is a sizable supply chain out there for these things. You can buy them

I am an engineer in a field that has been using >100VDC relays for a hundred years. There is a sizable supply chain out there for these things. You can buy them in whatever amperage you need, they just use different construction from typical low frequency AC relays. Wipers are often high quality metallurgy to extend life and they make use of simple passive magnetic snubbers to 'blow out' the arc that is self-extinguishing in AC circuits. They aren't substantially more expensive than regular high quality AC relays and use standard form factors.