[OP edited to change tense and to show correct steps, in italics] QGIS 3.10, Ubuntu 18.04
I was questioning why my map displayed at a +10 degree rotation, but displayed unrotated in the Print Layout.
What I did/do now.
Set Project->Properties->CRS to EPSG:5070 - NAD83 (Conus Albers)
Load 8 NED30m tiles covering the Grand Canyon.
Create a Virtual Raster from those and reloaded the .vrt file.
3.1 Change the newly reloaded VRT Layer's CRS to EPSG:5070
3.2 Zoom to that layer--to verify that it is indeed not rotated.
Export the zoomed layer as a Geopkg in EPSG:5070.
Restart QGIS, set Project->Properties->CRS to EPSG:5070.
Load the EPSG:5070-saved Geopkg as a new raster layer.
Verify that its Layer CRS is EPSG:5070.
Expect the layer to display with North UP, which it does, with the addition of steps 3.n and the edition of step 4.
The layer also displays properly in Print Layout.
[Harking back to my 4Y3M's-ago question, Project->ProjectProperties->General->CoordDisplay IS set to "MapUnits" as directed by AndreJ, whom thanks again.]
Q. Could someone explain why this is happening, and perhaps suggest another approach, or PCS, to reach my goal; namely, a large-format print of multi-tile b&w elevations? *The corrected steps result in a GCS layer exported to PCS to display squarely/rectilinearly in a PCS project.