I just moved to the Thunder app from Sync myself. Honestly, I still think the Sync UI is better, but I also know it’s pretty out of date. I know the dev often takes extended breaks, but I am tired of the complete lack of any communication. At this point, I have no reason to think that they are going to come back and push a newupdate for Sync. If they do, I will switch back, at least for a while.

Based on what you said, these are not required for you to do your job, only for you to improve your position. It is not unreasonable for you to use personal time for self-improvement. It’s also not unreasonable for you to use company downtime for self-improvement.