Probably not. It was almost certainly the case that these pagers were already connected to explosives, probably to be IEDs. All Israel would have had to do is page the pagers to detonate them. I can’t think of any other logical explanation.
I don’t think the thousands of pagers built this way really count as “improvised.”
That being said, it makes me wonder if this went in any way according to plan - 8 deaths and 2750 injuries is a large scale attack, don’t get me wrong. But they’ve now announced Mossad has compromised the supplier of the pager, which they will undoubtedly audit, and instill new policies on device security. I wouldn’t be surprised if that means they discover a lot more compromised electronics, allowing Hezbollah to pinpoint the compromise. Because 2750 survived, you now have 2750 people very interested in finding it.
In all, for 8 deaths, they’ve made their own work harder.
That being said 2750 injuries could be a large enough number to scare members out of the org.
I heard they recently switched to pagers because cell phones where deemed to be compromised. So I think besides the direct deaths and injuries, this attack also targeted lines of communication and trust in technology as a whole (or anything supplied by your superior even).