Its worth looking into chemical reactions. Keep in mind a bomb is anything that holds pressure until it suddenly doesnt. With a little ingenuity you can make almost anything into a bomb, and there are jo personel defenses and few vehicular defenses against a properly prepared bomb.

No gun will save you from the government. They will always have more force than you. But if you can force them to come to you, you can control where engagements happen. The geneva convention only applies to governments, the rest of the world is not going to care about you using biological or chemical weapons against your government.

Get a gasmask, bleach and ammonia mixed make chlorine gas. Leave barrels of gasoline around your property and practice shooting. You can get mercury out of old thermometers and use them to make tilt switches so that when someone steps on something, it activates. Timothy mcveigh (horrible dude, im not glorifying him here) showed how effective fertilizer bombs can be.

To be clear, im not advocating for any of this, simply listing your options.