Advice: get Apple Watch Ultra or cheap running watch for Spring Ultras?

I'm a regular Apple Watch (series 10) user and run about 40 miles a week. I like the AW for tracking runs and lifting all into Apple Health (I also use Bevel) and also very much appreciate the smartwatch features (Siri, easy texting, navigation, reminders, timers, find my watch). I do not like the look of any Apple wearable, but I can swallow that. Question is: I'm running 2 ultras in the next 4 months and will do some longer training runs before. The Series AW won't cut it. Should I buy an AWU, that I'll use all the time, or get a Suunto Run, Coros, or Garmin to become my new running watch. I'd then wear Apple Watch most of the time (including during sleep, which I like, since it's lower profile) except during runs. Anyone navigate this predicament?