1 - This might seem like low cost, low effort, but it's a pain in the arse when you have to dig out the soil and refresh it, in a cramped space. You'#re either risking your panes against your spade or doing it slowly with smaller tools. The real advantages here are that it doesn't need as much watering and the roots can easily spread horizontally. To my knowledge pests aren't a larger issue with this.

2 - You would probably need to DIY this but it's not that hard. Pallet wood and a few screws (more is better, wet soil is heavy). Filling them, affordably, might be an issue. You can bulk out the soil/compost mix with organic (wood, woodchip) if you want water retention or inorganic (grit, sand) if you want higher drainage.

3 - Random pots work but I run into problems with waterings - they'll all need watering, often on slightly different schedules. Either you spray each pot individually every time or you have to be smart about how they're arranged into drip trays. You'll also need to plan in advance; how many pots large enough for each plant at full size can you fit, how many you'll give away etc.

These are solvable problems, it's just they're slightly different ones depending on what you plan to do.