Using up all my scrap-stash - purchased and hand-spun yarn!
Each square is 31 sts , as per pattern. I am weaving in the ends as I go.
It might take a while…

Stuck!
Have no idea how to finish of armscye and shoulders.
Taking a break to think and research.

I improvised triangles where necessary to complete the shape. Mostly decreasing on the sides.
One I found suggestions for the edge triangles:
For each triangle, do the following:
Setup: On the right side (RS), pick up 17 stitches in the “V” (8 each side, 1 in the middle)
Row 1: On the wrong side (WS), and every WS, slip 1 st. purlwise, knit across, knit into the back of the last stitch.
Row 2: On the RS, SSK, knit to middle 3 sts, slip 2, K1, psso (pass both slip sts over the knit st), knit to last 2 sts, K2 tog.
Repeat steps 1 and 2 until 5 stitches remain. Bind off in Purl.
(After first decrease row, 13 sts remain; after second decrease, 9 sts remain; after third decrease, 5 sts remain.)

Another fill-in triangles suggestion is found here:
Fill-in Triangles:
Starting at the lower left corner, pick up sts along the edges of the squares
where you’ll make a triangle (slipped sts of the lower square, CO sts of the
upper). The sts picked up should be the same # as the st count of your squares
(mine are 31).

R1: Without casting on any sts, K2 of the picked up sts, leaving several inches of tail, turn.
R2: sl1p, K to last st, k1tbl.
R3: sl1 purlwise, k to next picked-up st, K1.

Repeat R2 & 3 until (your st count -1 /2; for me, 15) the picked-up sts have been knit, ending w/R2. (All the lower square’s sts.)

Next row: sl1 p, k to 1 st before next picked-up st, k2tog, turn.
Next row: sl1p, K to last st, k1tbl.

Decreases:
R1: sl1 p, k to 2 st before next picked-up st, k3tog, turn.
R2: sl1p, K to last st, k1tbl.

Repeat these two rows until you have 3 sts left (2 triangle sts and 1 picked up sts).

Next row: sl1p, k2tog, turn. (2sts) (If you have 4 sts: sl1p, k3tog, turn.)
Next row: sl1p, k1tbl, turn.

Now, pick up the next triangle-worth of sts (31 in my case), and put the 2sts remaining from
the previous triangle onto the ndl with the new picked-up sts.

Next row: sl1p, k2tog, turn.

Continue triangle instructions from ** until you have filled all the triangles on one side of
your project.

Next, Make a half-size triangle at the corner by picking up the sts along the flat edge of
the corner square (in my case, 15 sts).

R1: sl1 p, k to last st, ktbl.
R2: sl1 p, ssk, k to last 3, k2tog, k1tbl.

Repeat these two rows until there are 5sts left, ending w/WS.

Next row: ssk, k1, k2tog
Next row: sl2tog, k1, psso.

Break yarn and draw end through final st.

Rotate blanket a quarter-turn (top). Same instructions, though picked-up sts will all be sl
st edges.

Rotate blanket a quarter-turn (R side). Same instructions, though picked-up sts will be
CO sts for lower square, sl st edge for upper.

Rotate blanket a quarter-turn (bottom). Same instructions, though picked-up sts will all be
CO sts.

Finished!
still need buttons and I-cord edging.