True (and there is a nice video from Tom Scott[1] where he uses one of those things), but almost no high-speed trains[2] use those parts, AFAIK.
[1] https://www.youtube.com/watch?v=6TLcaJdsRr0
[2] with the exception of a few "weird" Intercitys that take very strange routes to reach tourist destinations like Berchtesgaden
As one counterexample is enough to disprove your "[2]" :-) :
Until it'll be bypassed by the new Rastatt tunnel, there's at least one mechanical signal box left between Karlsruhe and Offenburg (Durmersheim) which sees regular and frequent intercity traffic. Until very recently there used to be another one immediately north of it (Forchheim) [1], but due to the construction works for the junction with the new high-speed line it was replaced with a new computer-based interlocking in 2018.
[1] And a mechanical block post in-between, but that one was more or less permanently switched out and was probably last used in 2009, when during construction works the parallel line via Ettlingen was closed,
If you look at the map, filter for active signal boxes only and also remove "Elektrische Stellwerke" from the default filter, you might be able to discover whether the are any other mechanical or electro-mechanical signal boxes left on any of the main intercity routes.
(And since you mentioned Berchtesgaden: It looks like that whole line was switched to ESTW-operation (for non-Germans: computer-based interlockings) in November last year.
[1] https://www.youtube.com/watch?v=6TLcaJdsRr0 [2] with the exception of a few "weird" Intercitys that take very strange routes to reach tourist destinations like Berchtesgaden