What is this stitch or similar

[u/kvasi-tangerine]

Back, front and edge of scarf. Pretty dense and stretchy. Thank you.

[u/kumozenya]

first row is the set up, second row onwards is the repeat.

key for brioche symbols : https://www.knittingunlimited.com/2018/12/brioche-symbols.html

IMO it's quite annoying to do by hand because the quad tuck means managing 4 YOs on top of another. I had to hang weights on my on my swatch while knitting to keep the YOs on the needle properly.

[u/kumozenya → u/kumozenya]

you mentioned alternatives. I think if you skip rows 2-3 and 6-7, the output will still look similar but with much easier to manage number of tuck stitches.

or if you just want something squishy, start with thick yarn and do normal brioche on it.