TUI uses a proprietary font, done by DaltonMaag. Don’t know if that’s the one you are looking for, because DM don’t show a sample of this exclusive font.

It is. 'TUI Type', by/from Dalton Maag.
daltonmaag.com/browse/custom/clients/tui
typografie.info/typowiki/index.php?title=Hausschrift-Liste_Unternehmen-zu-Schrift

Dav

Oh, yes. Thanks, Dav, for confirming. Greetings from Linz to Linz. ;^D

Thanks for the help!
nice sources

As alternatives, you might like DM's Tondo or FF Nuvo.

It also reminds me of ITC Adderville, though that's certainly more casual, and Cronos.