its possible, mosses and ferns can survive with ph this high. A few of the members on this site use plants in their african cichlid tank which has a ph of 8+
That's the problem. Your equilibrium CO2 will be so low in those conditions that plants will struggle to photosynthesize. Some plants which can achieve biogenic decalcification will make it, but at the cost of making the pH rocket even higher. I would inject in that water, even if only DIY, even in moderate light conditions.
Use of Flourish's Excell might be useful. It won't affect the pH, is easily usable by plants as a carbon source, and in a smaller tank like yours isn't too costly.
YES! There are a lot of us that use tap water in our tanks that is hard and have a high PH. My tap is: 9ph and 9-10dkh. I do inject C02 which brings the PH down to about 6.9-7.1.
If you have hard water as well, that just means less ferts are probably needed. Most low light plants do well in high PH. There are some high light species that I have tested that do prefer softer water, while others thrive.