>the concept here is to still have multiple screens and multiple PCs, but control them with same mouse and keyboard
I want more solution to this problem.
As someone whose job involves using multiple locked-down computers connected to different VPNs, tools like Synergy and Mouse Without Borders are non-starters because of the restrictions, so a hardware solution is needed.
The way I accomplish it is with a KM switch. As you might imagine, a KM switch is a KVM without the V (video) part. While I would like to recommend you search for them, the unfortunate fact is many search engines assume you've misspelled KVM and just show you KVMs instead. KM switches consequently have a chicken-egg problem of low supply, low demand, and high prices.
I most often use an 8-port Belkin F1DN108K only because one showed up on eBay at a very low price. I also use a lower cost 2-port Kinan KM1302.
Unfortunately, recent changes to Windows 10 no longer allow me to use these KM switches with more than one screen. The problem may be something introduced in version 2004. I also see it in 20H2. Might be an update that was added to both of them. Wish I knew, wish KM switches had some kind of priority support.
That makes me a fool around :D .. I'm completely unaware of KM ... as you said, I'm looking for more hardware based solution, that has for example multiple bluetooth devices (say 3x or 5x) on KM so that it can be actively connected to the multiple PCs and can switch seamlessly.