What factors influence which Pokemon appears as the daily guaranteed Pokemon encounter?

Because of COVID-19, a guaranteed Pokemon encounter occurs daily. This Pokemon has a white circle surrounding it.

I’m wondering what factors, if any, increase or decrease the likelihood of certain Pokemon appearing?

Based on my observations, but not on proven facts or large group results:

• Weather boosted Pokemon are more likely to appear
• Pokemon that are more common in the wild are more likely to be the daily Pokemon, for example Numel
• Pokemon that don’t appear in nests can be the daily Pokemon. For example, one of my guaranteed encounters was a Gible.
• It does not appear to be influenced by nearby nests
• The Pokemon is unlikely to be evolved and is never a legendary