Can we develop a virus which is amicable for us but deadly for SARS-CoV-2 and HIV?

Viruses are obligate intracellular parasites. They act like a living organism only when they infect a cell. Apart from some protein structures which help them to attach and enter specific kinds of cells, viruses don't have enzyme systems that can be used for activities like "destroying other viruses".

A virus can not infect another virus as this would be a one time action. Viruses infect cells in order to replicate, a virus can't replicate by using another virus. So if you engineer a virus which will attach and destroy another kind of virus, it will be no longer a virus, it will be an unnecessarily complicated antiviral drug.

In addition to this point, you should consider that our bodies have leukocytes (white blood cells) which can identify and destroy viruses. Some kinds of leukocytes also produce antibodies to fight with the infection agents. If you aim to engineer a bacterium in order to fight with a virus inside our bodies, first you have to provide that the bacterium will stay in the tissues of our bodies for a sufficient amount of time and/or its secretions which attacks to the virus will enter and stay at least in the blood stream. It is obvious that this approach is way more complicated and hard to achieve.

This is an interesting question I have not considered, however it does have some caveats.

The ultimate question is how is COVID-19 going to be assaulted? What is the interaction to eradicate the pathogen? If we understand this, we don't need to create a bio-weapon to destroy a virus.

Also if we understand this interaction, we should arrive at a suitable vaccine as a solution. There are many methods to develop a vaccine, as outlined here.

Bacteria and viruses are very different and are in-fact different organisms.

Within our gastrointestinal tract (The hole from our mouth to anus), live approximately 100,000 billion bacteria. Typically viruses - speaking generally - stay with someone for a short time-frame. So you never have more than one at a time really and most people live their life without any viruses.