I don't practice law in Texas either, but the statute says Texas Grand Juries have 12 jurors and 4 alternates.
Videoteleconferencing is allowed, when approved by the GJ foreman and the state attorney,only (as far as I can tell) for taking testimony of a peace officer. And then only if the "that provides an encrypted, simultaneous, compressed full motion video and interactive communication of image and sound between the peace officer, the attorney representing the state, and the grand jury." The peace officer has to affirm that only the GJ can hear his testimony and that it is not being recorded at his end (it can be recorded at the GJ end by the stenographer same as any other witness testimony).
When the GJ is in session the only ones that can be in the room are the jurors, the states attorney, the witness if any, and some approved support people like bailiff, stenographer, etc. It would be hard to guarantee this with Zoom.
Tarrant County website says the two GJs go through about 14,000 cases per year.
I also found it interesting that once they start, the GJ cannot adjourn more than three days without consent of the court.
More learning for me!
Thanks.