With the except of educational establishments, where iPads are centrally managed and support multiple users, the Apple ecosystem assumes that iPad and iPhone are principally single-user devices. Signed-in services associate with specific AppleIDs (which may be different) but the device itself always associates with the AppleID used to sign-in to iCloud - iCloud services being essential in managing the device and its various security features.
If you wish to keep some of you devices non-user-specific, you could [potentially] create a dedicated AppleID for the “pooled” devices - and simply not sign-in (or selectively sign-in) to other services such as Messaging, FaceTime, Music, iTunes & App Store as needed. The key here is for you to understand what you are trying to achieve - and the services that are needed to accomplish your aim.
Whilst not generally recommended (due to the “rabbit hole” of complexity through which you can rapidly descend if you don’t understand the implications), you can theoretically be simultaneously signed-in with as many AppleIDs on a single device as you have services - but you must be mindful of unexpected interaction between services - particularly in respect of Messaging services, and/or linking with an iPhone, where all kinds of woe may be encountered.
If you do as you propose, keep it simple. Be sure to understand which services are essential to the pooled devices - and limit them to functions you need. What you can’t realistically do [outside of managed educational computing environments] is to pick-up a shared device and perform a single-sign-on to a bunch of services.
Unfortunately, without a very detailed understanding of your specific need, a definitive answer to your application cannot be provided here. My advice - sit down and map out (on paper) exactly what you need and the function of individual shared/personal devices - then map the services/AppleIDs that are needed on each to provide the functionality that you’re looking for.
I hope this proves to be helpful to you, perhaps leading to a workable solution.
