I'm probably late to answer but try to lean more for Nalis' choice and don't interact with Thaumo I can show you the choices I picked if you want but I think the guide in the development log has it :)
Any Choice
Any Choice
Do not exchange phone numbers
Text Nalis
Any Choice
Tease Nalis about being late
Why are you acting like this?
I want him to explain himself (that's the choice I chose personally, I still got the ending but the guide does say to choose 'I don't want to talk to him)
I'll join them at the arcade
Any Choice
Any Choice
From here on out you got the Nalis ending :) So whatever you choose doesn't matter
If you're looking for the other endings, the creator made a guide in their development log!