I just bought a 2023 Si two weeks ago. I knew before I bought it that there was no spare tire. My 2015 Si had a spare. I too, am uncomfortable driving any distance with an inflator that is advertised as good for 20 miles. I did some looking around and decided to buy a high quality spare (Continental tire, jack, wrenches and canvas bag) from Modern Spare. It wasn't cheap, but being stranded in the middle of nowhere would quickly make me question any decision I made about not investing in a proper spare. I got the kit a week ago, and it appears to be quality throughout. I was initially thinking I would place the kit in the canvas bag behind the driver seat, as the back seat rarely gets used in my car. If I need the space, I can easily relocate the bag to the trunk. I then started rethinking things and decided to see if the Modern Spare tire would fit in the dedicated area in the trunk. It does fit. I then ordered the hold down wingnut and plate assembly for a regular Civic (part number 74650-T1W-A01). It works perfectly. The dealer said the styrofoam insert for the jack is $120. I will probably find a canvas bag for the jack and wrenches as that is a bit steep. As it turns out, I didn't need the Modern Spare canvas tire bag, and you can save a bit of money by excluding it. I am happy with the way everything fits and the quality. If interested, here is the website for Modern Spare:
Homepage.