I recommend the Ergodox EZ. I’ve been using mine for work for over 6 years, 40 hours a week and it’s still running and typing as good as the day I got it. It’s saved me an unreal amount of wrist and back pain because typing on it feels natural. Ergodox has other keyboards with similar split key setups too so once of those might be more to your liking. Check them out at zsa dot io.
There’s a bit of a learning curve, but if you’re already a person who types every day at 60-70 WPM or more then it won’t take you long to get used to it. Bonus: the keys can be reprogrammed at the firmware level so that you won’t need specific software to assign keys once it’s set up to your satisfaction.
I’ve used other mechanical keyboards that have a split setup. I’ve got a CloudNine C959 on my home computer which is decent, but it’s definitely different than the Ergodox. The C9 keyboard is like a regular keyboard that’s split in half whereas the Ergodox is a complete keyboard redesign. Both good but the Ergodox makes typing nearly effortless. Anyway best of luck on your search!
The importance of coffee in this equation cannot be overstated. If you’re worried, try having a 12oz coffee plus lots of water an hour or two before your appointment. Don’t hold it in all day before the appt, you might hurt yourself. Just goose your waterworks with coffee and stay well hydrated before going in and you should be fine.
Also, doctors know about bashful bladders so just let them know you might be a minute. You may also be able to collect a sample at home if you discuss it with them first(don’t roll up to your doctor today with a cup of unasked-for pee). You’ve got options. Just when you’re in the moment, relax and let the coffee do the work.