White elephant better fish?!!? Need some help with starting out.

Hey guys so. Last night at a Christmas eve party we did a white elephant exchange and what did I grab? A betta fish. In a bag. Was just provided with the little guy and food pellets. Now I've had bettas before as a kid and at least remembered that they need more care and space than just a vase like the people at the event were telling me to use 😬. So I fought to keep him in hopes of giving him a better life than any of the other folks at this event might but now I'm in a pickle. I'm broke from the holidays but I have a little left in savings I can use so what is the bare minimum of starting supplies I should get? Ofc a tank at least 5 gal. But should I worry about a heater and filter and decor right now too? Are there water conditioning steps should I take? I'm trying to research but there's so many articles and some simplified and affordable starting tips would be great while I wait to get paid again and get more gear for my little guy. Thank you all for any help!

Also included a picture of my new buddy. Any name suggestions are also welcome haha

Happy Holidays everyone!