Having the same issue here. Not an electron app though. Classic Swift app. My first time. Took me some time to figure out all the signing and now that is done, the notarisation has been running for 8h and it just says "In Progress". Wondering the same question: Is there a reason that this process takes an absurd amount of time? Will it always be like this or is this just a fluke and it was a bad time to try?

Update on my end. The first (ever) notarisation took 40h to finish. Then, it was all green. Just did my second one and it took 5min. Something that I learnt is that is worth doing the "Validate app" with custom settings, before the notarisation as that will help encounter problems with the final build. e.g. Not signing correctly embedded files.