What's your cloud/syncing setup for files, pics, mail, bookmarks, etc?

So I've spent the last few days trying to sync everything up between devices, with the following thoughts in mind:

1. how fucked am I going to be if a device gets corrupted/stolen/lost?
2. how can I easily access everything I need from a mobile device/device not belonging to me?
3. how can I avoid using services from the big tech companies, and keep things open source, as much as possible?

I'm by no means an expert in the field, and I'm hoping in this thread to get a discussion going as to the pros and cons of using different services/setups, to get a general idea as to what others are doing to keep their daily lives simpler and more secure, and to perhaps see what are the future steps for me to take when I feel like playing around again.

Servers & Storage
I span up a 25GB VPS with Vultr for 'active use data', and also took out some 'deep storage'(?) from Wasabi for things which I need to keep, but not really access that much.

Mail
Protonmail with custom domain. Using the ProtonMail app for mobile, and Linux ProtonMail bridge with Evolution mail for desktop.

Pics/Vids
Nextcloud autoupload feature on mobile automatically uploads my pics to an 'autoupload' folder on Nextcloud server. Here, I categorise pics into folders and share what needs sharing before deleting anything I don't need and wiping the pics on my phone.

Passwords
Nothing yet. Looking at getting KeyPass synced across devices.

Bookmarks
Again, nothing yet. Had Firefox Sync running to connect Fennec and Firefox, but am looking for a more open approach which involves Nextcloud somehow, and allows me to tag and order things more effectively as opposed to dragging things around in the sidebar.

Calendar/Contacts
Evolution calendar on desktop, simple calendar on mobile, hooked up to Nextcloud and all synced using davx5

Programs and General Setup
Here, I'd like to somehow take an image/backup of my Ubuntu configs of importance and experiment with getting my setup and customisaitons replicated on another machine quickly and without taking up too much space in storage (i.e. don't need to bakckup all my files as they're already on cloud).

Also, I am very curious as to whether anybody is using Syncthing across their devices? And if so, how are they finding the experience?