How to .format expressions like f string?

Question

Consider the following program:

$ python -c 'import sys; print(sys.argv[1].format(**dict(val = 1)))' "val={val}"
val=1

However, the f-string functionality is not available in .format:

$ python -c 'import sys; print(sys.argv[1].format(**dict(val = 1)))' "val={'1' if val else '2'}"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
KeyError: "'1' if val else '2'"

How can I use f-string formatting capabilities with format string and a dictionary both set at runtime?

I tried the following, however I do not know how to "trigger" f-string evaluation on a string:

python -c 'import sys; locals().update(dict(val=1)); print(sys.argv[1])' "val={'1' if val else '2'}"

I could do this and it works:

$ python -c 'import sys; locals().update(dict(val=1)); print(eval(f"f{sys.argv[1]!r}"))' "val={'1' if val else '2'}"
val=1

However, it feels way like a hack. Is there a better way?