ReaTeam/Doc is an open source project licensed under GNU General Public License v3.0 only which is an OSI approved license.
Replacement for Unity's built-in resolution dialog (aka Screen Selector) that was removed in Unity 2019.3. Works both up front (simply make it the first scene) and as a popup dialog (default key: ESC). Intended for development / testing purposes but can also be used in production.
A Petty Message to Game Devs
reddit.com/r/gamedev | 2021-04-08
But yes, Reaper is great and is the backbone of a lot of audio automation in the industry. If you're interested in that you can point the reaper executable at a file listing all your WAVs, output format options, and RfxChain references: https://github.com/ReaTeam/Doc/blob/master/REAPER-CLI.md