Another druid trick I found. You can cast Speak with Animals then switch that spell out with another prepared spell and keep the effect on yourself. So Speak with Animals only costs a first level spell slot. It doesn't use up a prepared spell slot too.
IMHO it's a pity they did not stick with "Druids will not wear armour and shields made of metal" as per the PH page 65
To be fair this was always a weird flavor rule rather than a hard mechanical limit. The rule says "you will not" rather than "you cannot" and offers no explanation as to what will happen if you actually try it unlike older editions. It is more like a legacy rule than something that matters a lot as far as game balance goes.
It also doesn't make too much sense in modern lore. Clerics can channel the life or nature domains just fine in metal armor and they're drawing from basically the same source if they worship a nature god. Wizards don't suffer casting penalties in heavy armor so long as they have the proficiency. And I can't imagine a dwarf druid who grew up underground around metalworkers would consider worked metal to be more unnatural than treated wood or cured animal hide.