I believe that most, if not all of the Texas troops in the Houston/Galveston area had virtually disbanded prior to the surrender.

5/18/65 In a last ditch effort to bolster morale, Smith took a stagecoach [from Shreveport] on 5/18 bound for Houston in hopes of mustering more men. Along the way however, the remnants of his army further dissolved when Gen Buckner, acting in Smith’s name, surrendered the Trans-Miss Dept on 5/26. Finally reaching Houston on the 27th & realizing that he had virtually no troops left to command, Smith reluctantly agreed to surrender his forces & did so officially on June 2nd in Galveston Harbor aboard the Fort Jackson

5/21/65 Magruder to Gen J E Harrison cdg Bgde-Your dispatch rec’d. The Galveston garrison must be evacuated or else it will leave. I have great confidence in you & your Bgde & desire it to be concentrated at Camp Lubbock until the garrison has passed through Houston to their homes. Meantime your transportation can be gathered to you & in a few days you will be sent to your homes comfortably & respectably. Let the rest of Elmore’s Regt come as already ordered. They will be sent to you at Camp Lubbock as soon as the rest of your Bgde arrives there.

The Campaigns of Walker's Texas Division by a Private Soldier Blessington, Joseph Palmer, 1841-1898
The morning of the 19th found the majority of the troops
gone or preparing to leave. They were allowed to take a
wagon to each company. On the evening of the 20th, the
balance of the troops that remained were furloughed, or,
more properly, discharged from the Confederate army.