This is only if you really do want to make a change. Mini ITX, that you travel with a lot, I would probably be more inclined to say the R5 3600, now, over a 9700k, as the power usage/temps would be better. Plus given how the cooler assembles, you do not have to worry about it coming off too easily, during travel.
The 9700k can be quite power hungry, in comparison. I didn't think about the 9700k's lack of a cooler, earlier, either. If you are using the stock cooler, from your i5, it won't be enough to handle an i7, so that would be an additional expense. It isn't even really adequate for what you have now, imo. You might also need new ram too, as Ryzen should be paired with faster ram.
The 3600 would hold up longer, due to more threads, and will probably have far more consistent performance, than the i5 you have now. Frametime variance can be an issue with i5's, in newer titles. Honestly, though, I would not go below an R7 3700x, for a rebuild such as this, as it will have even more staying power, long term.
Personally I would go ahead and get your graphics card, first, and see how the performance is. If you are happy with it, I would wait on the CPU.