Is there a popular small signal PFET equivalent to NFETs 2N7000 or BS170?

That is called a complementary transistor.

BS250 is complementary to 2N7000.

Check this list for PFETs with the characteristics you want. However I don't know what popular transistors you'll find there.

ZVP3306A is not too bad a choice as a complimentary part to the 2N7000, rather cheaper (~30%) than the BS250, but it is still more than six times more expensive than the surface mount SOT-23 BSS84.

The 2N7000 is not good for 500mA, so you're not really looking for the equivalent (and you'll probably be pushed out of a TO-92 package into a TO-220 such as the IRLIB9343PBF if you insist on through-hole).

Again, if you are willing to use SOT-23, you can get a part that meets all your other requirements for less than 1/10 the price... for example the AO3403, which is almost magic- 30V, 2.6A, and it turns on quite well (200m\$ \Omega\$) with only 2.5V. Only problem it that it is SOT-23.

Consider the design to be sustainable, 2N7002 usually is used to control signals. You can use BSS84 as equivalent but pmos usually is used as power switch. that's why people rarely can find 2N7002's equivalent. They just use 2n7002 to turn on a PMOS power load switch.