Yet another Cyrillic version of Computer Modern fonts
The Cyrillic Modern fonts are based on the Computer Modern fonts designed in METAFONT by D. E. Knuth and released in the Type 1 format by the American Mathematical Society under the SIL Open Font License (OFL). The Cyrillic Modern fonts are intended to make the Cyrillic letters with classical shapes typical to the modern fonts. Currently, the fonts add support for the Russian language, the numero sign and quotation marks required for the Russian typesetting.
Modified version of the Fira Sans fonts to replace the default system
...In the alert about the package coming from an unidentified developer, click "Open" again. Follow the instructions in the installer and restart your computer when the installation process has finished. It is recommended to shut down, turn off, and restart your computer to finish the installation of the fonts. A simple reboot may lead to garbled dialogs, so a complete shutdown is highly recommended.