Texas has no personal income tax. For Texas-based nurses, federal rules drive almost everything.
If a 1099 business (such as legal nurse consulting) becomes an LLC: a single-member LLC is a franchise-tax taxable entity. It must file an information report even when no tax is due. The 2026–2027 no-tax-due threshold is $2.65M in revenue. A sole proprietorship isn't a taxable entity.
Working in another state on contract may create a nonresident return there if that state has an income tax. Ask your CPA.