Remote access Mikrotik with no public IP

You can not, simple like that. It is likely that even IF you manage - which I am not sure you could - the result would be you getting fired because of you going around the business internet policy.

The problem is that you have no public IP at all and VPN is not allowed, and NAT is not - that rules out all possible ways to communicate via IP, which the internet needs.

This smells brutally like a business or internet provider telling you that internet is NOT for publishing anything - and bypassing this is not a technical question. Besides being off topic, you open yourself to criminal prosecution and immediate job loss. Do not do it.