As I am now in FRance and travelled yesterday and then overnight to the south a few points to clarify due to recent topics raised. These are from trying out on the long-distance (purple) machines to see how it works and what is available. These machines work the same all over FRance. There are also blue machines for local tickets only without any REServation and the like.
It takes a fairly long way but it is possible to make REServations as passholder (differntiated between IR and EU and for both 1st or 2nd). Set up trip, probably for ´later/other station´ then there follows a very long list of types of pax (age, help needed for handicap, etc.) and then a page for ´reductions´ (I always use the French text-you can set them to /en/ and mostly also /de/). Click on MORE/autres there comes the Ir/EU option etc.
It will take a few seconds but then appears an overview on date/time chosen for connections and prices to pay. To my utter amazement sometimes it even showed 2 connecting TGV for 10€ together (for roughly 1 month advance). Machines now only take bank/crd cards for payment.
You can also REServe a couchette (budget sleeper) on the few overnight train they have for 21.50 and then have to give full details (name+adress, fone nr, mail, more), but this may then have been due to covid-measures-these have all been dropped 2 days ago (no more masks etc.).
Yesterday eve I could even see there were still a few 10€ quote seats on TGV from Paris to south for today-but at very early/late times.
The NOMAD trains to certain Normandie cities can also be found this way-these cost 1,50/ride. BUT some are shown as 9,50-it appeared these were with change from a bus to other railhead included, so it seems its 8€ for the busride.
NOTE also that in the past there were a lot of local TER buses in regions included-often THIS IS NO More-as these are being integrated in the regional transportation networks and then charge these fares-mostly quote low though-1 or a very few €.