Using a 2010 iMac 27'' as second display for a 2017 5K?

Hardware
1

I have an older 2010 iMac 27´´ sitting now right next to my 2017 5K.
I know this

paper from Apple about using the 2010 as a display with target display mode, and as I am running Monterey on my 2017, this seems to be not an option anymore for me.

So, does anyone know an other, really working, way to use the 2010 as a second (or in my case rather 3rd) display for my 5K?

2

The only “reasonable” option is Luna Display, which has been reported to be “laggy”. There are “unreasonable” options, though…

3

Luna Display requires a Modelyear 2011 or later, so it will not work in my configuration.