If you're banned or blocked or otherwise can't use a platform where you want to reply to someone, I suggest this:

We can reply to screenshots on nostr with the hashtag #replyaway and mention the username, and then anyone can find their away-replies on nostr by searching their username with the hashtag.

Can also link to a specified post, so later we can have bots that notify people on other platforms if their posts are linked with the hashtag on nostr. If those platforms ban those bots, they'll be laying out a clear division between echo chambers and nostr where you're actually allowed to know about everyone else's opinions if you want (because nostr will never ban bots from telling you if your posts are linked elsewhere, you'd be the one choosing whether to mute those bots)

nostr:note14xexwd8mm6j4klt82l7vnm6kp8hpa944dhlc4sgy2qt04gxua9sqrtvjac