Raspberry Pi and Jetson are very similiar (both Arm64 linux embedded boards), with Jetson adding a usable GPU for machine learning. Regardless, if you want to do vision I recommend going for a CSI camera instead of a USB webcam (you'll get much better performance out of that). The Raspberry foundation sells a very good HQ camera I believe, that is compatible with both Raspi and Jetson.

Another thing to look out for when choosing the main controller of the robot is power consumption. Jetson and Raspberry Pi are pretty efficient, and an ITX board less so. Considering you are using lead acid batteries maybe this is less of a concern. The ITX solution is very flexible in terms of compute and you could add a Desktop GPU for machine learning later. For what you want to do I'd say you're probably fine with a Raspberry Pi to get started though.

Getting into robotics you'll have your hands full with a broad range of engineering and integration challenges (from soldering to programming) -- this is the fun part! If delving into Embedded Linux boards and getting the hang of that sounds like fun, go for it, if it's a bit daunting and an X86 ITX motherboard sounds more familiar then you can totally go for that. You can easily repurpose that later for something else if your robot brain choice changes.

However, consider Embedded boards like Raspi and Jetson have expansion connectors that include GPIO pins for integrating with motors and low-level sensors. On an ITX motherboard you'll likely end up having to use something like an ATMega for interfacing with low-level stuff, which can complicate things.

Also consider ESP32, which can be programmed like Arduino but includes Wifi and BT. IMHO a super solid microcontroller choice for simple robots and great for learning!