The usual and expected set of vertical glyphs is included, some of which are region- or language-specific. In addition, all glyphs for kana, meaning not only those for small kana, include a vertical glyph variant. A small number of vertical glyphs happen to be encoded for compatibility reasons, most of which can be found in the U+FExx range, but they are still accessible via the 'vert' GSUB feature as vertical variants of the horizontal forms that are encoded elsewhere.
The pre-rotated non–full-width glyphs that are typically accessible via the effectively-deprecated 'vrt2' GSUB feature have been intentionally excluded from the glyph set.
It says,