@louis i would keep the two systems separate. You don’t want to have a limited range of roofers able to fix roof problems, nor tie the failure mode of one roof to failure mode of panels and inverters etc…
Doing the panel system after the roof is best, and having some solar installers provide feedback on roofing plan may help ensure any tricky spots or materials align between the two.
We redid our roof, conventional tar shingles prior to putting up our solar install. i preferred separate systems for the reasons i stated, also able to optimize solar components and use US made panels. Lastly, we had tree coverage that we expected to change, when it did three years later, we easily extended the separate solar system.