import scipp as sc
da = sc.DataArray(sc.arange('x', 2))
ds = sc.Dataset({'a': da})
sc.concat([ds, ds], 'y')

gives

<scipp.Dataset>
Dimensions: Sizes[x:2, ]
Data:
  a                           int64  [dimensionless]  (x)  [0, 1]

which is the input dataset.

concat works when concatenating in an existing dimension. And it works for data arrays.