Presentation slide length

I am new to presenter and am trying to figure out the best way to make an auto-advancing 3 or 4 slide presentation with each slide lasting 10-15 minutes. This would be a background for the sermon. All I have found is a slide length up to 30 seconds.

I honestly don't know why this isn't possible anymore. About two Years ago i used this for announcement Slides with just regular slides because Announcements couldnt do it back then. There was a possibility to set the time manually. I dont know about 10 minutes but at least 5 i think.

a very hacky and janky way to fix that issue might be to create videos from those slides and play them after one another

There are different ways of doing this, depending on what you are starting with.
If you have a PowerPoint file, when you insert it into the service, flag it as 'View Presentation with PowerPoint'. Then, any animations, including slide transitions, will play exactly as in native PowerPoint (because that is what it is)
If you are using the Presenter slide editor, in the Advanced Cue options, there is the option to move to the next slide after a timed interval, and then return to the first slide if you want to loop. Note that the same time applies to all the slides in the pack. I use this every week for the Church notices.