@mxnerd
Except for the fact that a Router or L3 switch can get beyond that by either adding a static route to advertise the path or using dynamic routing see each other. Consumer grade equipment doesn't really support this but even the basic Cisco gear does,
In a DIY scenario though the gloves come off and you can do whatever you want . Adding loopbacks / VL's / routes / etc. It depends on how complicated or streamlined you want to make things. I setup secondary loopbacks to pin services / servers to in my box instead of having to deal with docks / VM's running them individually within the OS.
GW 192.168.0.1
Pihole 192.168.0.2
Loopback 192.168.0.50
AP 192.168.0.65
Some other things like Webmin just use the LO and port differentiator 10000 or Plex LO 32400 or ntopng LO 3000
Seeing those "apps" as an extension y using a different port but the same main number being the LO.50
Seeing the PIHOLE / AP as different numbers completely outside of the main company instead of extensions.
The inverse is possible though reusing the same IP network and segregating it using VLAN's by invoking the tags to keep them seeing each other / communicating with each other. From a logical standpoint in engineering it's easier to pick an octet and match it to the VL ID i.e. VL 5 could be 192.168.5.x or 172.16.5.x or 10.x.5.x
In bigger networks we typically use 10..x.x.x and the 2nd octet might be used to indicate a different location.
10.214.x.x would be Dallas
10.212.x.x would be NYC
10.202.x.x would be DC
There's usually some logic behind the numbering where it's an area code or something else that's commonly known or you end up using a spreadsheet since you have locations that wouldn't be 1-254 for an IP.
Further segmentation within the parent IP scope comes down to the services needed and allocating the 3rd octet to that grouping for management purposes .
There's a lot of different approaches but, there's also ways to make things work improperly to get what you need to happen within the network while waiting on approval for new equipment. This is usually referred to as a "pinhole" to work around the constraints of current conditions.