This app has been released: https://portableapps.com/apps/office/bitcoin-portable
Download Bitcoin Portable 0.21.1 Dev Test 1 [18MB download / 52MB installed (excluding blockchain)]
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Bitcoin blockchain download [2021-09-06]
The Bitcoin Core Client is only available as a 64-bit Windows app. On first run, it will warn you about blockchain size to confirm you want to use it, ask if you'd like to run a full or pruned node and configure itself appropriately, and give you the option to download a pruned blockchain from us as a digitally signed self extractor so you don't have to download 385GB+ of blockchain and do a lot of extra writes to your device.
2021-09-06: 0.21.1 Dev Test 1: First release