Your competitor's app is just where one better customer task lives
What changed for your competitor's customers is probably one task: booking at 11pm, reordering in two taps, seeing when the technician will arrive. The app is just where that task lives.
That matters because the app is the expensive part. It needs regular updates as phones and app store rules change, someone to fix it when it breaks, and customers willing to download one more app. A website that does the same one task well can get much of the benefit for less running cost.
So start with your own customers. Ask ten of your best ones what they wish they could do without calling you. If the same answer keeps coming back, you have found the thing worth looking into, whatever form it ends up taking.
Then look at the competitor's app as evidence. Read its reviews and check when it was last updated. Reviews that keep mentioning one feature show you what at least some of their customers care about.
Finally, ask whoever quotes you for an app what it costs to run in year two and year three, and who does that work. Most quotes stop at launch day.