Edit: and Intel doesn't and won't play into the market for support chips. There's no way in hell that they can support Intel's required profit margins.
It's kinda both. To be clear, EUV directly refers to a specific type of lithography equipment, ones using extreme UV light sources. However, those changes come with a lot of changes in larger process flow that are all inter-related.
The change in EUV means smaller lithography lines, and also means needing photo resist, etching, cleaning, etc. - many other process steps, that support that size change. Add in that now, with EUV lithography, you are operating lithography under vacuum and its a huge challenge. Suddenly you have to have vacuum ready materials.
One of Intel's mid 2010 wins was getting immersion litho to work better than peers - similar thing just wet wafers rather than vacuum wafers.
EUV is a tool/technology, one used only on critical layers where that precision matters (e.g., gate patterning). But the larger (entire) manufacturing process has to be designed to enable the use of that tool/technology.