Kyle, I think what you linked to is more like a routing switcher, a sort of valve that can let any one thing at a time go thru and throw it to a projector or video wall. You’re asking about putting up multiple things simultaneously. For that, you could use an actual video effects switcher, you know, with rows of buttons marked for camera 1,2,3, etc. and inputs for graphics sources and video playbacks, and controls for cropping, scaling, and moving the images around within the video space.
There are also boxes called screen splitters or multiviewers, that will allow you to put multiple inputs onto one screen, and if your needs are truly modest and never-changing, maybe that’s enough to crop and scale one camera and a powerpoint screen into your monitor or projector. You can think of these as the devices used in security systems to show multiple security camera feeds on one monitor. Here’s just one option. https://www.blackmagicdesign.com/products/multiview
There are also sophisticated multimedia presentation apps like Wings and Stumpfl, which I’m not really qualified to talk about. Others in this forum live and breathe that stuff and could better advise you on the utility of them.
But for worship applications, many churches are happy using a Newtek Tricaster, which is a sort of all-in-one “tv studio in a box”, that gives you the video camera switching, character generators for text and titles and even scrolling song lyrics, special effects, and digital motion video playbacks, all neatly integrated. It also records the show to internal memory and can stream it live too. They are a kind of “Swiss Army Knife”, and come in various levels of cost and ability. There are other ways to do the same thing – another popular option these days is based around the Black Magic Atem virtual switcher, which runs off a PC platform.
The flexibility of a video production switcher lets you handle a lot more things on the fly IMO than a simple scaler or multi-view splitter.
If you check out the blackmagicdesign and newtek web sites you might see something that works for you there. You can also shop B&H Photo-video’s web site with a search for Video Production Switchers and set it to list by price to see what level of capability is generally available for the budget you have in mind.