MeWe - Recommended Facebook replacement.
MeWe is probably the closest like for like replacement for Facebook, with similar features (minus the ads and spyware).
If you are technically minded you could consider building and/or hosting a site for you and your friends. Projects like Friendica and Hubzilla could help with this.
Gridsome - Recommended Gatsby replacement.
Like Gatsby, Gridsome collects data from various sources and generates a static site from it. Gridsome is a Vue alternative to the React based Gatsby.
For static site generators more broadly, also take a look at Eleventy and Hugo.
Vue - Recommended React replacement.
If you are willing to try something less established, Svelte and Alpine.js both make for interesting alternatives.
Telegram - Recommended WhatsApp replacement.
Telegram is a messaging app, available for all popular platforms. It looks and feels a lot like WhatsApp, and can serve as a direct replacement for it.
If WhatsApp wasn't a perfect fit in the first place, apps like Signal or Discord might better suit your needs.