Yes, a bridge is the phone, so you have: sensor -> phone -> display on smartwatch.
Yes, sometimes you can run without a bridge, I'm speaking specifically about XDrip+, though it's not particularly straightforward which of the Google watches actually work and how well right now.
I'll point you at these as at least a starting point, but I'm not sure how up to date they are:
Enhanced personal research version of the xDrip android app - jamorham/xDrip-plus
The last thing to mention is that libre3 support is still somewhat in development - as far as I understand it's possible to get it all running using a modified app, however I've not seen any detailed instructions (nor have I looked though, as I'm still using libre2 and haven't been forced to move to libre3 yet. At that point I will need to review what I do: Android phone -> Garmin watch)
Sorry that's not all that useful, hopefully it will point you in roughly the right direction.
Once you've had a read around, and if you decide to use XDrip+ (there may be other viable options of course) there is a discussion "forum" here where you can ask questions:
https://github.com/NightscoutFoundation/xDrip/discussions and there's a chat channel here:
https://gitter.im/jamorham/xDrip-plus
P.S. If you used the dexcom with something like XDrip+ you should be able to calibrate it so it actually works for you and gives the numbers you want.