I think if I were to post screenshots I'd have to have it hosted by another provider to post a link. My 'self-hosted' FOSS cloud service has limitations and so I can't do this.

I use all of the FOSS services you mention but also became unstuck there too. When I started posting on SN and started to see nice previews of tweets. I was surprised as this differed from what I created when posting Nitter links as my nitter links didn't generate previews.

After realising this, I just converted my nitter links back to twitter ones before sharing/posting them.

So, I can understand what you're saying, but for me I'd have to wait for the hard-working volunteers at SN to figure out how Nitter links could, in the future, generate previews.

Till then, I'll just get these fat fingers to 'reconvert' converted links...

It's a hack I know, but I don't really mind hacks - my love of DIY hacks¹ helped bring me to this space after all! 🧡

¹proper tech hacking/work-arounds (not 'cracking')