It’s a day of work to implement the DRM, not the mod itself, which he did release day 1 for free on Nexus, only the frame gen version is behind the patreon wall, additionally he’s released many such DLSS+FG mods for various games (which all come with the sub) so he has a lot of experience implementing it and has clearly gotten it down pretty well.
Every game has its own challenges but Starfield was particularly easy (according to him) because of how FSR was implemented