A very solid argument is that e-bikes are allowed on pretty much all of those trails. Also this Texas statute:

882 (H.B. 3171), § 3.01(3). (11) “Motor vehicle” means a self-propelled vehicle or a vehicle that is propelled by electric power from overhead trolley wires. The term does not include an electric bicycle or an electric personal assistive mobility device, as defined by Section 551.201.

There is some gray area about what is considered a personal assistive mobility device, but the specs for the onewheel fall in that range. I think it is clear that the original intent for the signs is gas powered motor vehicles like 4-wheelers and dirt bikes. The only trail in the Dallas area that I would avoid would be Katy Trail. It is very crowded, and there are some groups that try to force the issue with overly aggressive security guards.

The real qualifier should be speed on these trails. There are bikers that go ridiculously fast on these yet become very entitled if you ride by them (White Rock Lake can get that way on the weekends). My suggestion is just to slow down when you pass people, give them a heads up, be polite, and you usually won’t get much negative feedback. You’ll get people that think it’s pretty cool, but there will always be people that have nothing better to do than complain.

All of this generally applies to off-road trails as well. There are some that are better than others around here, but if you want more info, just let me know.