Not system-wide audio, but per-tab: there’s a browser extension that puts subtitles over whatever is playing in the tab, transcribed as it plays. It’s in the Chrome and Firefox stores now, free and AGPL like the rest. It won’t replace OBS + localvocal for anything outside the browser, but there’s no filter chain to set up — install it, open the tab, hit Start.
Two things to set expectations. It runs behind the audio: it transcribes in windows, and on integrated graphics that’s tens of seconds, so the overlay prints how far behind it currently is rather than pretending it’s live. And it only works where the page itself plays the media — a site embedding someone else’s player in an iframe, or a file served without CORS headers, can’t be captured at all, and it tells you so instead of sitting there.
On permissions: it asks for no site access when you install it. When you hit Start it requests that one site, and nothing else.
For the whole workflow you described—cuts, face blur, and subtitles—I would still use Kdenlive or Shotcut. A subtitle-only tool will not replace tracking a blur or arranging clips. If subtitles are the part making the editor feel heavy, you can split that step out: generate and proofread an SRT first, then bring it into the editor for the final render.
OpenSubs has Linux desktop builds for that subtitle step: it can generate and edit subtitles, export SRT/VTT/ASS, or burn them into an MP4. The builds are unsigned, and burn-in requires an ffmpeg build with the ass filter. (Disclosure: I’m one of the developers.)