I am starting with No One Lives Forever 2, as this was the hardest to come by and I only got its French CD original.
This is a DirectX8 game, so it did run on Windows 11 25H2 but had no picture output while running.
1) For fixing this, I have downloaded dgVoodoo2 and Copy D3D8.DLL from the MS\x86\ folder to <path-to-game>.
2) Enable v-sync in video options as suggested by PCGamingWiki
3) Download the Updater to French Patch 1.3 (else, use the English version)
This fixes the no sound in cut scenes and in-game issue.
As I do not know French, I now downloaded and installed the Patch ver.1.5 for No One Lives Forever 2 contains 6 European languages GUI
This includes the 1.4 patches and allows to set the GUI and subtitles to the language of your choice. I decided for English.
I did not have any of the other issues described by PCGamingWiki, hence I did not require further patches.
Next one is Contract J.A.C.K.
I initially thought, following this extensive guide is good enough for single player.
However turns out, no picture under Windows 11 25H2, without downloading dgVoodoo2 and Copy D3D8.DLL from the MS\x86\ folder to <path-to-game>.
After having followed and done both, the game runs beautifully! 🙂