Iris and Nostrgram have an option for this and there is also sites like https://nostrgraph.net/archive or https://nostryfied.online/ for backups.
I pulled my followers via Iris today after it was nuked yesterday. Had to refollow everyone manually.
Discussion
What was nuked yesterday?
My following list. When I came online I was following 0 people. Fortunately this isn't Twatter and we're all kinda following the same plebs but it still took me about 2 hours to refollow (most) people through other profiles... if you know what I mean.