This seems like a very worthwhile project and I'm glad you're issuing an RFP to find qualified individuals/groups to carry out the goals and gain the outcomes.
We carried out a similar project about 30 years ago which led us to develop Peer Resources, the only organization in Canada that specialized in peer support for youth. We no longer do any training, but we did produce dozens of training guides, research papers, and a considerable website resource.
Since our hundreds of youth trainings across Canada, we moved to a train-the-trainer model and we also expanded our scope to include youth programs connected to mental health centres, hospitals, community agencies, colleges and universities as well as thousands of elementary and secondary schools.
My advice to you is to no rule out what has been developed and learned in school-based peer support in your aim to focus on lived-experience mental health support. We learned early on that the principles associated with effective peer support programs, particularly those run by and for youth in education had much more in common than different from those programs run outside education system.