DevOps was (and is) merely an excuse for companies to replace Developers with cheaper Ops resources, and yet expecting better services and better products from them.

My personal experience says that the best way is that Ops team shouldn not be repurposed as Developers, rather put the experienced Developers into Production Support (incident management, that's intense Ops, working in shifts and weekends, etc.). And rotate them whenever needed. Over a period of time, you'll invariably see less defects and issues percolating down from the Devs, and then after both sides are stable and working well together with less friction and open tickets, then some more tech savvy Ops members can be rotated into Development teams as rookie devs to help reduce costs a bit (as there'll invariably be some natural attrition among the Devs and Ops, so this gives an alternative career path to the Ops team (who are usually less paid, and more stressed), and pushes the Devs not to become complacent). Such an approach is doable and productive.