We use OKRs across the business indeed. We have Company Objectives set up-front in half-yearly company planning, with functional objectives spinning out of those. Each function (Product, Engineering, Marketing, Ops) has their own OKRs that roll-up to the overall company objectives.

Marty Cagan indeed talks about using OKRs to replace roadmaps, but I think both can exist in unison. For example, we also switched to OBRs (Outcome-based Roadmaps) which helps teams align on how a feature in the roadmap may achieve a certain outcome that drives a Key Result. Check it out - a good guide from David Denham here.