Pre-launch hardware startup: what's the best way to get early pre-orders when you know your ICP but have no marketing background?

We're a pre-launch hardware startup in the elder care space (ambient home health sensors for aging parents). Product ships later this year. Right now we're collecting pre-orders with a $50 refundable deposit to validate demand.

My question is about the most effective way to get those early pre-orders without burning cash on ads before we've nailed our messaging.

We know our ICP well (adults 35-55 who are worried about a parent living alone and are weighing options like assisted living, caregivers, etc). We know where they hang out online and the physical places they show up.

What we're debating internally is whether the best use of our time right now is:

1. Going directly to where our ICP gathers online and engaging authentically (answering questions, sharing what we've built when relevant)
2. Doing in-person outreach such as showing up at senior expos, caregiver meetups, even leaving flyers at relevant locations
3. Running small-budget Meta/Google ads to test messaging before scaling
4. Some combination we haven't thought of

For those of you who've sold a physical product pre-launch: what actually moved the needle? Was it community engagement, paid ads, partnerships, or something else entirely?

Would love any hard-won lessons. We're first-time founders and have no sales background.