I guess it might depend on which Akibahara store you’re going to, but at least a good number of them when I went this year (IMO) are just too ‘generic’ with a lot of the floor space dedicated to just the most popular franchises, with uninspiring merch (e.g. tshirts, acrylic stands) that can easily be found online.
Stuff in Nakano Broadway (where a large portion of the floorspace is dedicated to Mandarake’s secondhand shops) are rarer and more diversified, and there’s even a shop selling original animation cels of old anime (I was salivating over a Cardcaptor Sakura one which cost JPY500,000…). There’s also the JOJO bar which is insanely cool.
I browsed r/JapanTravel a lot to look up tips and general recommendations.
There are a lot of internationally recognized calculations and reporting methods and companies can hire consultants who can estimate the emissions in their end to end supply chains.
There are also calculators online that can give an example on what elements are considered, e.g. the below from UN.
https://unfccc.int/documents/271269