It doesn't work for painting.
If your paint has body and texture, such as lime washes with granulation, it also fills a bit. But Q2 still won't be enough.
You can, however, scrape off a filler very sharply with a trowel. Of course, a spatula or plastering trowel also works, but you also want to finish the job inside the house. I would also recommend stainless steel. If you're doing this for the first time, you can easily round off the tool corners; otherwise, you risk scratching your surface. But yes, deburr well and don’t bend it!
You don’t need filler a millimeter thick. If you scrape well, there is little to no need for reworking, and it’s best to remove that with the trowel instead of sanding.
I like to use filler from Pufas because it doesn't sink in. However, it is not mineral-based and therefore not always desired on every surface. I don't like to use hardware store products. I also only buy the ready-made buckets now, no more powder. Ready mixed from the bucket is simply faster, and you don’t have leftovers.
Good luck Gabriele