Hi Jen - you articulate what I'm sure is a big button pusher for many emergent souls when in family....
Where the people around you don't honour or respect your expressed truth. It's especially hurtful when they're supposed to be your loved ones.

How to deal with the conundrum - what is it revealing about our own journey of self-realisation?

Firstly, here's what stands out about what you express...

I do tend to feel victimized by it and call out the situations as I experience them - though it feels like speaking to others in a foreign language...it leads to more feelings of isolation, being attacked, misunderstood, and generally "othered".

This is quite typical - so why does "calling it out" not seem to work? The clue is in what you say here...

I feel intense headache and burning in my eyes, tightness in my solar plexus and my jaw and so much frustration at feeling out of place - deeper than that is the feeling of not belonging and not being seen or understood and that what I feel and think don't matter.

It's clearly karma, YOUR karma, which you realise is why you manifested the situation. But what is the karma exactly?
I would point to the feeling of isolation that you express. What is the problem for you to be isolated - from ignorance?
Can you sit in the isolation with family members around you and not need to express your truth?

Remember the Jesus quote: "don't cast your pearls before swine, less they trample them".

When we try to sew our seeds of authentic expression in dense soil that has no nutrients, then we'll keep diminishing our energy - we'll keep depleting ourselves and get frustrated and exhausted by it. So why do it?

I would say the squirrels are demonstrating this very accurately...

a few determined squirrels) have uprooted or eaten everything I've planted. Each day I have gone out and reinvented a new version of reinforcement for the plants. I've learned how to build many structures and persisted in my efforts to protect the plants, but now I wonder if the sun will even get through enough?

We have to accept it - for some people around us right now, the sun is NOT going to get through enough for them to see some light and wake up.
So stop wasting your efforts by trying to plant truth in unsupportive ground. Sit in the tightness of that, and the apparent isolation - I know the desire is to reach out and illuminate. Work to let that go. Find peace with your own internally expressed truth - look for the feedback loops with the Universe. You'll always find some sun shining there 😉

Love and well wishes

Open 🔆