You can also feed in without a bidirectional meter. The grid operator is obliged to purchase photovoltaic electricity under the Renewable Energy Act. Yes, the problem can therefore be convincing the grid operator of their obligations, but that should not be the reason for failure.
Of course, you can feed in without acceptance of the system and without a bidirectional meter.
But then you are already moving in a certain criminally relevant area.
There is no acceptance from the grid operator without a new meter. And as already mentioned, there are thousands of photovoltaic investors who have been waiting for exactly this acceptance for more than 1 year.
Better buy yourself a rotary engine than give stupid advice here.