Congrats on the new tablet! Switching ecosystems can be super stressful, especially when you depend on it for work. Since you are moving around a lot, honestly, you should prioritize protection first. I have been using the Spigen Tough Armor Pro on my gear for a while and it is a lifesaver for drops, plus the kickstand is solid. Just be careful installing your screen protector because dust is the enemy. I really like the Paperlike Samsung Galaxy Tab S9 Matte Screen Protector for that drawing friction, but definitely watch a tutorial first so you dont waste your money on a bubbly install. For the keyboard, keep an eye out for sales on the Logitech K380 Bluetooth Keyboard, it is super portable and the battery lasts basically forever. Since you are doing heavy multitasking, you might want to consider a decent USB-C hub to keep everything connected, just make sure to get one with power delivery so you arent draining your battery. I would suggest picking up a small carrying sleeve too, just to keep the screen safe in your bag between cities. Moving gear around is risky, so take it slow and dont rush into the expensive stuff until you really need it. Let me know if you run into any trouble getting it set up, it is a great piece of kit once you get comfortable!

Regarding the Spigen choice, it is okay but honestly kinda bulky. You need to check out these instead for your travel workflow:

• INFILAND Samsung Galaxy Tab S9 Case
• iVoler Samsung Galaxy Tab S9 Screen Protector
• Arteck Universal Bluetooth Keyboard

Yep, this is the way