I use PyCharm for work but it’s not FOSS or beginner-friendly. PyCharm does have a free community edition which is awesome if you’re mostly into FOSS for the $0 aspect.

• https://thonny.org/ - for the first few days of learning and easy setup
• https://www.spyder-ide.org/ - especially good for data science
• https://eric-ide.python-projects.org/ - full-featured general purpose IDE

Codium is fine and technically FOSS although it’s association with Microsoft taints it for anyone who still hates MS from the bad old days. Also it’s an Electron app.