I'm a newbie, too, having joined this forum on 2/27/23, the day before picking up my 2019 Insight EX from a Honda dealer in a bordering state. My Insight came with an unused spare tire but no jack, tools, or foam insert.
This forum provided a wealth of info on possible solutions. One post provided the part number for the foam insert made for the Insight, it's part number 84541-TXM-A10. It's horseshoe shaped rather than round. Some members advised in older threads that they couldn't get one due to back order or unavailability.
I Googled the part number and found several Honda dealers that sell on-line at discounted prices. Checking the part number on their websites, some of the sites showed the part as discontinued or unavailable at this time, I could not add it to the on-line shopping cart. However, one website, HondaCarPartsDirect.com, showed the part as available and you could add it to your shopping cart. I emailed HondaCarPartsDirect.com asking if they could confirm whether the part could really be ordered.
They emailed back stating "This part is available at our primary warehouse which would take about 2 business days to receive in stock." So yesterday I ordered it along with a couple of other accessories including the trunk tray. We'll see if they end up including the foam insert with my order or refunding me due to unavailability. MSRP of the foam insert is $43.40, HondaCarPartsDirect's price is $32.55.