If you only consume the content from your follows you are indeed safe but thats not a social network experience

If you want to potentially be exposed to content of follows of your follows its approximately 100k-100kk users which kinda could work on a moderate gaming pc but def not a regular tier-2/tier-3 smartphone

If you want to see more 🤝🤝🤝friends of friends connections you need a solid hardware cluster given that at least some activity happens 

 100k-1kk* of course 

 Not enough for temporal responsibility.

Add a zero tolerance. 

 The follows of follows is a very moderate number and even if it were a million, that's very much manageable. You throw them into a cockoo filter that's far less than 1MB and you can filter by that set trivially in RAM and CPU.