package, only available from stretch-backports, however that version may be outdated, dysfunctional:
Not as simple as just installing the package.
Tails design documentation:
https://tails.boum.org/contribute/design/#index55h3
Tails config:
https://git-tails.immerda.ch/tails/tree/config/chroot_local-includes/etc/skel/.electrum
Tails user documentation:
https://tails.boum.org/doc/anonymous_internet/electrum/index.en.html
Existing Whonix documentation about electrum:
https://www.whonix.org/wiki/Electrum
Electrum Bitcoin Wallet in Whonix ™ Development Notes:
https://www.whonix.org/wiki/Dev/electrum
Criteria for installing applications by default in Whonix:
https://www.whonix.org/wiki/Dev/Default_Application_Policy
Policy for Inclusion of Compiled Software:
https://forums.whonix.org/t/policy-for-inclusion-of-compiled-software/6635