UpdraftPlus backs up your files into ordinary zip files (the same format that WordPress and its plugins and themes directories use). The database is backed up into an ordinary SQL (text) file.
Therefore you can use UpdraftPlus to restore backups, but do not have to. You do not even need WordPress installed. You can just unzip the zip files, and use your web hosting company’s control panel to import the SQL into your database.
We are committed, as a fundamental of UpdraftPlus’s design, to retain this situation. UpdraftPlus backups will always be something that you can restore with standard tools. There will be no proprietary lock-in.