• Get Reaper. It’s a mainstream DAW, is fully functional, a free download, and only $60 to register after 90 days.
• Valhalla Supermassive for reverb: https://valhalladsp.com/shop/reverb/valhalla-supermassive/
• The VST fork of VCVrack for a modular synth: https://github.com/bsp2/VeeSeeVSTRack#downloads
I would get a keyboard controller with full sized keys and a 5-pin DIN MIDI out for just over $200, but that can come later.
One thing to avoid is the rabbit hole of concentrating on what gear to buy over actually making music with the gear.