Lirr is not usable yet in tsw2. It will come with the next set of preserved collection, approximately this week. https://live.dovetailgames.com/live/train-sim-world/articles/article/tsw2-roadmap-1-september
You need to own the add-ons (purchased them individually or through a bundle) to use preserved content as far as I'm aware. Game Pass is not ownership of the game or included add-ons. If you buy TSW2020 (should have a Game Pass discount), you will eventually get LIRR, Main Spessart Bahn, Northern Trans Pennine and Great Western Express to use in TSW2.
In the live stream last night, Sam said if you’ve spent money on a particular DLC outside of Game Pass that is yours and you can get it free on TSW 2 as a preserved collection DLC. If you’ve only played the game using Game Pass and not bought anything separately, you won’t get access to that in TSW 2.
Any DLC you have purchased and spent money on will be carried over with the preserved collection, the core game however you will need to buy. You do not own any of the games through Game Pass, try to think of it a bit like renting the game with the subscription. Not all of the preserved collection is currently on TSW 2 yet, but take a look at the roadmap to see what's currently being worked on. Hope this provides some clarity.
If you have Gamepass, then you don't own any of the games. It's kind of like Netflix, you pay a subscription, but you don't own any of the films or other content.
So according to XBox store I own TSW2020, West Somerset, Rapid Transit and NEC New York. I've never bought TSW2020, only played it on Game Pass, but I did buy the original Train Sim World. Would that explain why I own the game and these routes? I have Northern Trans Pennine, Long Island and Main Spessart Bahn installed under Game Pass. Once these are made part of Preserved Collection, I understand that these would need to be purchased. Presumably this would be at the going rate of £24.99 and it would make sense to purchase the Collectors Edition of TSW2020 now?
Yes. TSW1 included Rapid Transit and NEC New York (this one isn't going to be available in TSW2). West Somerset I don't think that was in any bundle...maybe it was purchased at some point as an add-on or was it in a deluxe edition of TSW1... If you want the routes included in TSW2020, like LIRR, MSB and NTP, then that will need to be purchased. Peninsula Corridor and Ruhr-Sieg Nord will be in the Collector's Edition (best value for the amount of routes you get). This one did go on sale the other month but you can still get it on a Game Pass discount.