Apart from “configuring the box with WinSCP” which is not possible because it’s not an SSH client (use PuTTY not WinSCP) it is all technically possible but neither CE or EE natively support dual-boot via menus from the internal eMMC storage so this would need customised u-boot firmware. All the sources for that are available but it’s up to you to make the customisations; and my personal experience is that users who have the skillsets to do that don’t ask for guideance in forums because they can see how to do it and just get on with it, and the users who ask for guideance don’t have the skillsets needed. It’s a task that needs custom code writing so it’s not something you can do by reading HOWTO guides (that do not exist) or anyone sane will attempt to coach/spoon-feed instructions for.
So choose either CE or EE and put it on the eMMC storage, then put the other on an SD card. When the card is inserted you get one, and when removed you get the other. It’s not all driven by a remote control but it’s practical, low-tech, and will work.
Thank you very much for your reply. It is as I feared. I chose the VIM3 because it, along with the MINIX NEO U22-XJ Max and the Ugoos AM6B Plus all have HDMI 2.1 out. I wanted to future-proof the Kodi box as much as possible and thought that sometime in the future HDMI 2.1’s Dynamic HDR’s SEI messages might be important to CoreELEC and Kodi. That and the VIM3 and MINIX both have unlocked bootloaders which I thought would make using with CoreELEC & EmuELEC easier.
The rest of your points are quite right. I was hoping against hope to mitigate what I am now begining to think was the wrong purchase.