As for me, I will have these data backup into my external drive and definitely it would be a desktop type as I don't going everywhere with my photo backups. I also have an old HDD which is not reliable but I use it to backup my primary HDD.

As for those handphone photos, I did the same but there will be a copy in my google photo as backup or for sharing anytime. (Yup. when doing backup, do backup from your handphone and not download from Google photo. Original is the best. I you copy from google photo and you some how sync back to the server, when you delete your cloud image, it will remove your back up as well. Im not sure if this still happen but before I use google photo, I notice that.)