I'd wager the most efficient way would be to sell your electronics and donate the proceeds to a local charity that does this at scale and knows its way around local needs and regulations.
When I was a kid in Moldova a couple of decades ago, we had a lot of Americans donating their old stuff (electronics, clothes, shoes, even furniture) thinking they're being super helpful. Just had a quick search and it seems to still be happening to a small degree. It's a nice sentiment and I'm sure it makes people feel like they're making a difference, but economically it makes no sense. The cost of processing and shipping second-hand items is probably not much lower than just giving people money to buy locally, and supporting local businesses while you're at it.
Sort of unrelated, but the funny thing was these donations were often distributed by American missionaries who were using them as a pretext to hand out bibles (or rather just the New Testament). In Moldova, which by some metrics is the most Christian country on the planet after the Vatican. And the bibles were usually in English, a language almost none of us spoke.
Not to say that's necessarily the case for Uganda, but if the OP blog is any indication, they could have bought several second hand laptops for what it cost to ship one.