Why not test phonic knowledge (if it must be done) simply with the most common English graphemes.
Out of the 205 used for spelling English, quite a few are easy to read. -ance / -ence endings, for example, don't need special attention for reading, although tricky to spell.
Perhaps Maizie or Mrz can tell us which of the following does the Yr 1 phonics check test for?
And is just one pronunciation enough for the likes of a (and, any, apron)?
a, -able, a-e, ai, air, al, all, ar, are, -ary, -ate, au, augh, aw, -ay,
b, ca/o/ut, cc, ce/ci, ch, -cial, -ck, -cy,
d, -dge,
e, -e, ea, ear, ee, e-e, ei, eigh, eir, er, -er, ere, -et, eu, ew, -ey,
f, ga/go/gu, ge-/gi-, -ge, gh, gn, gua, -gue, h,
i, -i, -ible, -ic, ie, i-e, -ie, igh, -ign, -ind, -ine, ir, is, -ite,
j, k, kn, l, -le, m, mn, n, ng,
o, -o, oa, oar, o-e, -oe, oi, ol, oo, -oor, or, -ore, ou, ough, -ought, oul, our, -our, ow, oy,
p, ph, qu, qua, r, -re, rh,
s, sc, -scious, -se, sh, -sion, -ssion, -sure, -sy,
t, -tch, th, -tion, -tious, -ture,
u, -u, ue, u-e, -ue, ui, ur, -ure, -ury,
v, -ve, w, wa, wh, wo, wor, wr,
x, y-, -y, --y, y-e, z