Unbuttoned collar and loosened knit tie?

For an informal setting, with no preferred dressed code, what would you complement with a blue check dress shirt worn with the collar unbuttoned, and a blue knit tie?

I am debating whether a combo of sweater, chinos and dress shoes would be ok. I don’t own many sports jackets, and I’d rather avoid them.
What would you choose, and in which color?
Can’t wait to hear from you.