Hi I just made the switch to Affinity and I have to say other than the lack of Image Tracing I am loving it. I immediately fell for the Asset panel and started looking for Icons.
I found this post from a few of years ago: https://forum.affinity.serif.com/index.php?/topic/29075-icon-pack/
I like the packs, albeit a little out of date in 2021. However, I didn't like that they were all split into multiple files and that you can't merge categories. I decided I wanted to remake the pack, but I had no desire to painstakingly go through and name each SVG. So I created an application that reads individual SVG icons and merges them to a single file. I provide a colour change option so you can pick colours best suited for both Dark and Light themes.
Due to how this application works it will only work on Icon and will not convert complex multi-path SVGs.
Here is the application https://gcoulby.github.io/affinity-sprite-sheet-generator/index.html and here is a link to the repository (including basic documentation https://github.com/gcoulby/affinity-sprite-sheet-generator)
I have also included the asset pack which contains the same set of Icons (sans Gnome icons, which no longer exist) posted by @helmuthdu but they are contained into a single asset with subcategories
Entypo+: https://github.com/chancancode/entypo-plus
FontAwesome: http://fontawesome.io/
Foundation: https://github.com/zurb/foundation-icon-fonts
Game Icons: http://game-icons.net
Hawcons: http://hawcons.com/
Icomoon: https://icomoon.io/icons-icomoon.html
Ionic Icons: https://github.com/driftyco/ionicons
Material Design Icons: https://materialdesignicons.com
Material Icons: https://github.com/google/material-design-icons
Typicons: http://www.typicons.com/
icon_pack.afassets