XQquery for specific attribute of all specific elements in XML
Almost get it:

select
    d.lin.value('./@NetAmount', 'decimal(10,2)') as Amount
from
    t
cross apply
    data.nodes('ROOT/CATEGORY/PRODUCT') as d(lin);




| Amount |
| :----- |
| 10.50  |
| 20.50  |
| 30.50  |
| 40.50  |
| 75.50  |



db&lt;>fiddle here