Paid certificates without guarantees. Whatever one australia whatsapp number list may say, the most convenient to use and the most trustworthy services are American ones. Not all of them have announced their departure at the moment. You can take a risk and still buy an SSL overseas. But the experience of the last month and a half suggests that any carriage of foreign manufacture can turn into a pumpkin overnight, and you will again find yourself alone with the same problem.
No one will give you guarantees. Own certificates. No one is stopping you from making your own certificate, but the catch is that most Russian users are firmly "sitting" on foreign browsers, and they simply will not recognize your certificate. Free certificates. Many companies, such as Let's Encrypt, provide SSL certificates for free. However, there may be difficulties with their renewal.
Some hosters renew them themselves, while others require you to do it manually. You can simply skip this step. There is no technical support. If you choose the wrong provider, there is a chance that the certificate will not work. BUT! Even taking into account all the "ifs", at the moment this option seems to be the optimal temporary measure.