AWS Pinpoint short and long codes

Hi, I have couple of questions regarding long codes and short codes usage within Canada. To give you some context we have the following case - on the one hand users register in our app as business owners. On the other hand there are customers who use some services business owners provide through our app. Among other things business owners can run marketing campaigns through SMS channel and as a requirement they need to use their own either long code or short code for that ( toll-free, 10DLC and SenderID are not available as fat as we can see for Canada). We see tech possibility to request long codes through Amazon Pinpoint SMS and Voice v2 API for business owners https://docs.aws.amazon.com/pinpoint/latest/apireference_smsvoicev2/API_RequestPhoneNumber.html once they register in our app however as we understand long codes might not be suitable for A2P marketing type of messages. If this is true short codes look like something we should stick to however since it requires registration trough creation of support case it seems we can't create it automatically per each business owner that registers in our app so we need to create it just once and use for all business owners. Can you advice whether we can try long codes per business model or we must use just one short code per our app for all businesses?

Another question regarding that is that apart from marketing campaigns we have cases when we need to send system notification (on behalf of the app) through SMS e.g. customer invitation or remainders. Should we use short code for that?