It might not be technically possible, but you can use any Part 90 radio on any Part 97 frequencies legally, so it does not need the Part 97 TA.
Not sure what you mean not technically possible, but MANY commercial/public safety radios are readily programmed to Part 97. It used to require a software trick or a hardware mod (changing components), but most modern VHF part 90 radios are actually now 136-174 in one band split. UHF is often 400-470, 430-470, etc etc. Some require a software "key" to let them be wideband on ham freqs, but other manufs have already built the ham ranges into the wideband exceptions that would otherwise apply to part 90 channels.
That is legal (using a part 90 radio on part 97 amateur). In fact, there are many hams who use older (and some brand new!) public safety radios for ham use.
I'm not referring to using the inexpensive Chinese radios, I'm talking about Motorola, Harris, Thales, Vertex, etc.
edit: Re-reading your post, maybe you meant not technically possible as in some radios might not be able to work in the ham bands...I first interpreted it as a more general statement about the feasibility.