What "move towards nationalisation"? The whole thing has been operated under DfT^» (Department for Transport - about) control for over five years. So far I don't think any of the government-owned bits of it have been merged into the new operating structure, even in shadow form, and that includes what RDG^▸ (Rail Delivery Group, or Reading station, depending on context)/NRE^▸ (National Rail Enquiries) does.

For bookings we are still promised a single GBR^▸ (Great British Railways) service, which will remove anything for there to be differences between (within the railways, at least). Until then it's hard to see what kind of move towards that would make sense - you'd just get on and do it, wouldn't you? On the other hand, a TOC (whoever owns it) that ends up changing its software for some reason is hardly going to spend extra money on making it looked more merged for the short(?) interval before GBR gobbles them up.