10, soon deprecated, in general that's it? No, it'll not be fully so. Windows 10 IoT LTSC 2021 is to be supported up until 2032, that's plenty of time, folks. In addition Microsoft will allow to receive updates for non-LTSC, but that's paid.
There is no security or compatibility reason today to move to infamously bad Windows 11 unless one likes to have a headache. Want a different GUI, well, there are a lot of projects that reshape Windows 10 to look like 11, like XP, or 7, very nicely. If you want ever more customization, look into Linux, it respects a users and it doesn't force updates without an explicit permission, which has surprisingly good compatibility with Windows games by the way (thanks to Proton by Valve and Steam).
Please note that Windows 10 IoT LTSC 2021's ISO has significantly less bloat that is present in the non-LTSC version, it can be easily verified for free using Microsoft's site itself (Visual Studio Subscriptions Portal, enable showing all, then click Info to see the SHA256 checksum), and then it'll receive updates for free for a very long time if you're worry about that and want your machine to live and happy. It feels to me like not many know it's an option here, and I hope this post can change that.