You can install Win11 on there with a workaround (
example), but it's not officially supported. Right now, it's technically capable of it, you can
enable the fTPM 2.0 already in 100-series, the CPU should know SSE4.2, so the latest Win11 24H2 should run fine. However, any future feature upgrades, like the upcoming 25H2, will likely also check the compatibility again before their automatic installation, which will then probably deny installation. So the big updates would have again to be installed using a workaround, be prepared for a bit of manual work to keep this going, once a year or so.
But yeah, i've put Win11 on PCs before where the CPU was not officially supported, it's not something forbidden. You just have to know what you're getting into. And yeah, from a Z170 board, it's probably a good excuse to really upgrade the system from top to bottom (don't forget about the
PSU).