Are there gas ovens that come with a thermometer?
Many ovens in the US have such a feature.

However, ovens lie.  Even if thermostats and thermocouples in ovens were scientifically accurate (they are not), they are positioned on the outside walls of the oven, not the center of the oven where you are actually doing the cooking.  This might not be an issue if you are baking a frozen pizza (if this is the level of cooking you are intending on doing, go for it, and use such an oven), but would be a problem if you attempt any sort of finicky baking.

Don't trust the knob or readout on your oven, it isn't telling you the whole story.  If you need precision, use a bulb style thermometer on the center rack of the oven.  And unless you have very basic oven needs, don't let the presence or lack of a thermometer be a prime purchasing decision.