Just here to second this idea. I’d really like to be able to supply my own sticker pack for other team members to be able to use. We have a substantial amount of branded art we could use.

Another voice just to second this: Yes, please, please add that! Especially helpful for branding reasons and also just to personalise your Miro boards more easily!

I would like to +1 this! I would like very much to do custom stickers for my studio to use 

Being able to add in a custom pack, especially for assets that relates closely with the purpose of the board/presentation/collab would be extremely beneficial. In my case, it would be for facilitating some training workshops.

The current sticker collections are super fun and I heavily use them, but there’s not much options for stickers that have more of a classic/minimalist/elevated feel. 

Can’t wait to see new items pop up!

While not a solution, I will still take a few minutes to share a lesser known feature called Saved Files as I didn't know about this for my first year of using Miro, and even shared this with another long-time Miro user the other day who was floored by its existence.

In short: add a file to a board (JPG, SVG, PDF, etc.) and then add it to your saved files. Now the file is available to you on any board in that same team (note: the files are saved at the team level, so if you're constantly moving between teams, you would have to repeat the above steps at least once in each team).

More about this feature here:

https://help.miro.com/hc/en-us/articles/360017731013#h_01EKYVYMMGPSMW7G43JV8YJ5YB

I’m not sure if this is the same or a different workaround as what @Robert Johnson  said above, but what I and another teammate did was made our SVG icons in our preferred program, and then created a template that we saved to our team templates. We can then import that entire template and use the icons we need for our layouts and drop downs.

Here’s an example of the “Map Key” template I made, which uses icons from several other templates we made (as examples):
 

Another template I made for our network callouts:

One more option if you have someone with a development background in your organization is to create a quick “drag and drop” app that could be installed and used by any team member. Miro even has an example drag-and-drop app that could be installed and up and running in a few hours:

https://developers.miro.com/docs/add-drag-and-drop-to-your-app