Project description
It's Microsoft's new Edge browser based on Chromium. It just released today with a .deb download we could easily extract and turn into a package.
Metadata
I've already made it.
To try it out:
git clone https://gitlab.com/zanc/overlays.git
cd overlays
nix-env -i -E 'f: with import <nixpkgs> { overlays = import ./overlays.nix; config = { allowUnfree = true; }; }; microsoft-edge-dev'
I get an error when I run edge from your overlay:
[1023/171818.277793:WARNING:process_reader_linux.cc(125)] no stack mapping
[1023/171818.277847:WARNING:process_reader_linux.cc(125)] no stack mapping
[1023/171818.283521:ERROR:elf_dynamic_array_reader.h(61)] tag not found
[1023/171818.283556:ERROR:process_memory_range.cc(75)] read out of range
[30430:30430:0100/000000.373734:ERROR:sandbox_linux.cc(374)] InitializeSandbox() called with multiple threads in process gpu-process.
fish: 'microsoft-edge-dev' terminated by signal SIGTRAP (Trace or breakpoint trap)
Works fine here.

Tested on 20.09.
$ nixos-version --json | jq ''
{
"configurationRevision": "98ed418720e329a69a310e277f45b1430540b937",
"nixosVersion": "20.09.20201020.05334ad",
"nixpkgsRevision": "05334ad78526ead39af85f846515606d9f052a11"
}
@zanculmarktum here's what I get:
strip is /nix/store/p792j5f44l3f0xi7ai5jllwnxqwnka88-binutils-2.31.1/bin/strip
stripping (with command strip and flags -S) in /nix/store/sgm01jabgf4f8hwggy2jj0sgw06gpj1r-microsoft-edge-dev-88.0.673.0/bin
patching script interpreter paths in /nix/store/sgm01jabgf4f8hwggy2jj0sgw06gpj1r-microsoft-edge-dev-88.0.673.0
/nix/store/sgm01jabgf4f8hwggy2jj0sgw06gpj1r-microsoft-edge-dev-88.0.673.0/opt/microsoft/msedge-dev/xdg-settings: interpreter directive changed from "/bin/sh" to "/nix/store/2jysm3dfsgby5sw5jgj43qjrb5v79ms9-bash-4.4-p23/bin/sh"
/nix/store/sgm01jabgf4f8hwggy2jj0sgw06gpj1r-microsoft-edge-dev-88.0.673.0/opt/microsoft/msedge-dev/microsoft-edge-dev: interpreter directive changed from "/bin/bash" to "/nix/store/2jysm3dfsgby5sw5jgj43qjrb5v79ms9-bash-4.4-p23/bin/bash"
/nix/store/sgm01jabgf4f8hwggy2jj0sgw06gpj1r-microsoft-edge-dev-88.0.673.0/opt/microsoft/msedge-dev/xdg-mime: interpreter directive changed from "/bin/sh" to "/nix/store/2jysm3dfsgby5sw5jgj43qjrb5v79ms9-bash-4.4-p23/bin/sh"
checking for references to /build/ in /nix/store/sgm01jabgf4f8hwggy2jj0sgw06gpj1r-microsoft-edge-dev-88.0.673.0...
patchelf: cannot find section '.dynamic'. The input file is most likely statically linked
patchelf: cannot find section '.dynamic'. The input file is most likely statically linked
building '/nix/store/dd7niwfw4cgakjx02jy99wh31l2ld0qx-user-environment.drv'...
created 3 symlinks in user environment
Actually it runs when you append LD_LIBRARY_PATH, i.e.
$ LD_LIBRARY_PATH=/run/current-system/sw/lib microsoft-edge-dev
Not sure why this is the case.
Most helpful comment
I get an error when I run edge from your overlay: