As to the shared db aspect, while spitting a miniservice into micro ones I had this situation. All the code was split first and the db changes being the most difficult to was done last as a point.of we don't expect to revert this.choice. We weren't at a performance limit so that was fine, any schema changes had to be clearly communicated and coordinated. In all not too bad. I don't think I'd want to leave it in that state as a normal state. The point of micro is Independence and isolation of changes and sharing a db leaves a sensitive area. Don't let that stop you if it's only a temporary state. Just get commitment as to how temporary that is, since in absolute terms everything's temporary.
I feel the OPs pain but I’ve built MSAs from DDD principals and it really is a better architecture for complex systems.