You can claim your partner as a dependent if you pay more than half their living expenses and they have less than $4700 of taxable income (or $5050 for 2024). Many forms of disability payment are not taxable but some are, and even if they receive non-taxable disability that does not count for the income text, it still does count for the support test.
And you are correct, this type of dependent does not make you eligible for HOH status.
