@JHenAptive Yes, @timl is correct for SharePoint List. It is still not supported for SharePoint List. It may not be in the future either. It is only for data sources like Dataverse and SQL Server
For example if I have a SharePoint List like this:
And a formula like this
Upon clicking Run OnStart:
The Collection shows all the columns, not just the ones in the LookUp.
In my case I had only Title in the LookUp.
If Explicit Column Selection were working on a SharePoint List, I should only see the Title, not all of the columns.
so you are right @timl , SharePoint List as of this writing, are still not supporting Explicit Column Selection yet, and it may not in the future as well as it is probably only supported for data sources like Dataverse or SQL Server.
So @timl is correct, for your case @JHenAptive you should not worry about the Explicit Column Selection.
However, if you ever are considering to use Dataverse in the future, or any other kind of data source which may support Explicit Column Selection, you should be proactive and potentially be already concerned about writing the formulas as if they were explicitly selecting columns, now, to make moving over to Dataverse later much easier.
You can also simply turn off the Explicit Column Selection feature and use Datavers without it on until you can rewrite all the formulas, but I recommend leaving the setting on.
If you're pretty sure you may stick with SharePoint, then I recommend not worrying about it.
However, you may get performance concerns when you have a large amount of columns, like maybe hundreds of them for example in a SharePoint List, this is because ShrePoint List, as @timl mentioned, does not currently support Explicit Column Selection. Even in the hundreds of columns I am often OK with using SharePoint List on my end but depending how many Records, how many Lists you are using and how many columns each list has, how you are using the formulas, etc. you may start getting issues at the higher end of number of columns.
You may have to break into separate SharePoint Lists that have fewer columns when this happens to improve performance.
If it gets too unwieldy to manage you may want to look at Dataverse, or moving some of it over to Dataverse and keeping the SharePoint List for others (Canvas Apps support using multiple data sources at the same time)., making sure to keep the Explicit Column Selection setting on to best leverage Dataverse.
However, SharePoint List is very powerful, so I may be able to continue using SharePoint Lists, even when some others may already consider to move to Dataverse.
However, whenever the concern first arises to use Dataverse, it's often best to act on that initial hunch, as in the long run it may be easier to manage in Dataverse, and the extra cost of Dataverse is usually less than the cost of the troubles one may encounter when not acting on that initial hunch.
I am probably biased towards keeping SharePoint Lists, even when it may actually be better to move to Dataverse, as often there is a lot of desire to avoid Dataverse and avoid the extra licensing cost.
However I have found in most cases, I would say the extra cost of Dataverse is actually much less than the cost of the extra maintenance overhead, and having to use advanced techniques, when keeping SharePoint Lists. So when people tend to try and save money not using Dataverse, they may be paying more in the long run (and even in the short run) by working so hard to keep the SharePoint Lists.
Nonetheless, SharePoint Lists are so powerful, that I may keep them well before moving to Dataverse, and I recommend you start with SharePoint Lists first.
