Injured and uninsured in Texas: does applying for Medicaid trigger a Special Enrollment Period?

Texas, missed open enrollment on HealthCare.gov, currently uninsured. Income should be above ~100% poverty level ($16,400) so likely ACA-eligible but not Medicaid. I have a leg injury that might need surgery and trying to figure out if this path actually works.

1. If I apply for Medicaid in Texas now and get denied, does that reliably trigger a Special Enrollment Period for ACA plans with subsidies?
2. How long does a Medicaid decision usually take in Texas (days vs weeks)?
3. If the injury happened before coverage starts, is any part of treatment covered at all?
4. Has anyone actually used this route successfully in Texas, and were there delays or issues?