Both the iPad Pro 2018 and the Galaxy Tab S7 Plus are powerful and capable devices that can handle video editing and digital art creation. However, there are some differences that you should consider before making a decision.

In terms of video editing, both devices can handle the tasks you described, but the iPad Pro may have a slight edge in terms of ease of use and available apps. The iPad Pro is known for its smooth and intuitive user interface, and it has a wide range of high-quality video editing apps available, such as LumaFusion, which is a powerful and feature-rich video editing app that many professional editors use. The iPad Pro also has a larger display, which can be helpful when working with video.

The Galaxy Tab S7 Plus also has many video editing apps available, including PowerDirector, which you have already tried. However, some users have reported that the Android user interface can be a bit more cumbersome and less intuitive than the iPad Pro.

In terms of your use case, both devices are portable and lightweight, making them a good choice for travel. However, the iPad Pro may be slightly more convenient for digital art creation, as it has support for the Apple Pencil, which is a high-quality stylus that many artists prefer.

As for the refurbished iPad Pro vs. the new Galaxy Tab S7 Plus, it really depends on your priorities. The refurbished iPad Pro may be a good option if you are looking to save some money, but you should make sure that it is in good condition and comes with a warranty. The new Galaxy Tab S7 Plus, on the other hand, will come with a manufacturer's warranty and may have slightly better hardware specs than the refurbished iPad Pro.

Ultimately, both devices are capable of handling your needs, so it comes down to personal preference and which device you feel most comfortable using.