At long last I did the merging to get the Git parts up to date
(expand for gory tig output 
)
M─┐ [git-objects-develop] Merge branch 'store-path-or-ca' into git-objects-devel
│ M─┐ [store-path-or-ca] {obsidian/store-path-or-ca} Merge branch 'store-path-de
│ │ M─┐ [store-path-descriptor] {obsidian/store-path-descriptor} Merge remote-tr
M─│─│─│─┐ Merge commit 'f7f1be69330212d22c11027adb4bd8a07c1f56fe' into git-objec
│ M─│─│─┤ Merge commit 'b21dd384235bc9863c89ef249bbc1ca58f4ec3fd' into store-pat
M─│─│─│─│─┐ Merge commit '7cac155fc8b548de7b4e054aee66551e2fc93289' into git-obj
│ M─│─│─│─┤ Merge commit 'c67e0cc58c5a74121d74a3f5cf9f9c2199a87093' into store-p
M─│─│─│─│─│─┐ Merge commit '6208375ba942a676da12e79c135e07eb585cd9b0' into git-o
│ M─│─│─│─│─┤ Merge commit '6601ac86421fb05377f113aa52c55da7b9cbe658' into store
M─│─│─│─│─│─│─┐ Merge commit '6305b77a2878333bf2af208ffe691d10ad233812' into git
│ M─│─│─│─│─│─┤ Merge commit '056cc1c1b903114f59c536dd9821b46f68516f4e' into sto
M─│─│─│─│─│─│─│─┐ Merge commit '9faa690e0fd8ff3d8d53e5df1c4b3c969a52fc3a' into g
│ M─│─│─│─│─│─│─┤ Merge commit '2e7be46e73293f729358eefc5b464dcb7e2d76bf' into s
M─│─│─│─│─│─│─│─│─┐ Merge commit '3a43680ff89cc3bba167773c32dbc3762148857e' into
│ M─│─│─│─│─│─│─│─┤ Merge commit '91617f80ec03ff4580a656310959ce2e31e0d177' into
M─│─│─│─│─│─│─│─│─│─┐ Merge commit 'c08971bf2df0bfa0deb2b58451ebf3a65f1e0f72' in
│ M─│─│─│─│─│─│─│─│─┤ Merge commit '46e942ff9e65755689ee72f93846d7118e1b8d45' in
M─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '554158c9d06ab90f261812ddc81ad5f682f2918a'
│ M─│─│─│─│─│─│─│─│─│─┤ Merge commit '9cfa78e58a92b4bf034867bc1296a200bdc3f12a'
M─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '17313408d5c06ae6aac98f7d35d8da6195c4ab2b
│ M─│─│─│─│─│─│─│─│─│─│─┤ Merge commit '6a168254ce068c067259c913ee7d6ee2e0d1dc7e
M─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '50803f208da7a8f37d31191df7f32ad6b764ee
│ M─│─│─│─│─│─│─│─│─│─│─│─┤ Merge commit '8623143921f8683b88d46aaebe9f707e5b9a91
M─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '4ed87aac038f307dcdf069835b9b7aa6de24
│ M─│─│─│─│─│─│─│─│─│─│─│─│─┤ Merge commit 'e9fc1e4fdb0ab5adb6b163c3db361b86a4f5
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ {obsidian/git-objects-develop} Merge commit 'daa
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit 'fa1e9ea950d735e078ce360ccdea94f3
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '56be25a069df3d9aadf8e0b714e205
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '230c771713ddaeb1d0cdfa70e3e8
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '5e87f0884c93ee91803e835a05
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '4ed2f421eb707c2195927db2
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '8106a67e4e6f403be65e18
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '27ef76ab58e5ebeb2d98
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '8f0b757a9524af47bf
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit 'e6ad49075907a2bd
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '4a55c7b74b0de4
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '37ab1891b9de
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit 'f1bcb730a9
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '7f50ecf5
o │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ │ Introduce experimental
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge commit '554f00
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge remote-track
M─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─│─┐ Merge remote-tra
As a result, we have this draft PR Git object hashing in libstore by Ericson2314 · Pull Request #8918 · NixOS/nix · GitHub
Thanks to @matthewbauer in particular who, back in 2020, wrote most of the underlying implementation.