Little Fish, Big Pond
To anyone that will listen to me, I encourage them to optimise their podcasts for Apple and Spotify. Why? Because Apple has by far the largest share of the market, with Spotify in second place (but growing and clearly ambitious, with some big budgets to play with). My source is '99 Firms' so the data is somewhat US skewed but the wider article contains much food for thought.
And as with social media platforms, it's a good idea to "super serve" one or two of them - and get it spot on - rather than spread yourself too thinly.
But... but... but....
You don't need to reversion your podcast for any of the 'minnows' - and those minnows together make up a decent chunk of podcast listening. Stitcher, Amazon, Anchor, Pandora and iHeart Radio (admittedly more US based), even the BBC Sounds app has some interest in independent productions.
And I won't go into the as-yet-unproven world of 'Clubhouse' - although maybe I will another day - which a number of podcasters are getting somewhat excited about... although I see it occupying a space outside of traditional podcasts.
So - if you want to ensure every possible listener is available to you, it's worth looking at whether your podcast is landing on as many of the minnows as possible. For a start, they might be minnows today but sharks tomorrow. But also, as somebody in the radio world told me years ago, "be just as great at 3am as you are at 8am... the 3am listener might only ever listen at that time of day". It's worth being available in as many places as possible with relatively small effort, to pick up those "3am" podcast listeners.
And... don't ever forget YouTube. Whether it is for short clips (maybe with your Zoom video and subtitles) or the whole podcast, it's a great audio repository, a great search engine, and another opportunity to showcase your podcast... maybe to people who don't think they DO podcasts and become converts to yours.
It just goes to show that my mother was right. There are always more fish in the sea.