To read the json.bz2 files you can use the following code in python:

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#!/usr/bin/env python

import json, bz2
from pymatgen.entries.computed_entries import ComputedStructureEntry

with bz2.open("2021.04.06_scan.json.bz2") as fh:
  data = json.loads(fh.read().decode('utf-8'))

entries = [ComputedStructureEntry.from_dict(i) for i in data["entries"]]

print("Found " + str(len(entries)) + " entries")
print("\nEntry:\n", entries[0])
print("\nStructure:\n", entries[0].structure)
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The meaning of the columns in ps_scan_summary.txt is

 1. chemical composition
 2. number of sites
 3. volume of unit cell optimized with the PBE functional; For licensing
    reasons, we do not include the values from Materials Problem and AFLOW.
 4. volume of unit cell optimized with the PBEsol functional
 5. total energy per atom calculated in PBE functional at the PBE
    geometry. For licensing reasons, we do not include the values from 
    Materials Problem and AFLOW.
 6. the total energy per atom calculated with the PBEsol functional at
    the PBEsol geometry
 7. total energy per atom calculated with the SCAN functional at the
    PBEsol geometry
 8. band gap calculated with the PBEsol functional
 9. band gap calculated with the SCAN functional
10. total magnetic moment per atom calculated with the PBEsol functional
11. total magnetic moment per atom calculated with the SCAN functional
12. (3 values) diagonal of the stress tensor calculated with the SCAN functional
15. comment. If the primary entry is originally from Materials Project or AFLOW, 
    it contains the ID of the entry. If the geometry optimization required a
    larger cutoff or more k-points, this is indicated by a "R".

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This is the list of vasp PAW setups used:

Ac PAW_PBE Ac 06Sep2000
Ag PAW_PBE Ag 02Apr2005
Al PAW_PBE Al 04Jan2001
Ar PAW_PBE Ar 07Sep2000
As PAW_PBE As 22Sep2009
Au PAW_PBE Au 04Oct2007
B PAW_PBE B 06Sep2000
Ba PAW_PBE Ba_sv 06Sep2000
Be PAW_PBE Be_sv 06Sep2000
Bi PAW_PBE Bi 08Apr2002
Br PAW_PBE Br 06Sep2000
C PAW_PBE C 08Apr2002
Ca PAW_PBE Ca_sv 06Sep2000
Cd PAW_PBE Cd 06Sep2000
Ce PAW_PBE Ce 23Dec2003
Cl PAW_PBE Cl 06Sep2000
Co PAW_PBE Co 02Aug2007
Cr PAW_PBE Cr_pv 02Aug2007
Cs PAW_PBE Cs_sv 25Jan2019
Cu PAW_PBE Cu_pv 06Sep2000
Dy PAW_PBE Dy_3 06Sep2000
Er PAW_PBE Er_3 06Sep2000
Eu PAW_PBE Eu 23Dec2003
F PAW_PBE F 08Apr2002
Fe PAW_PBE Fe_pv 02Aug2007
Ga PAW_PBE Ga_d 06Jul2010
Gd PAW_PBE Gd 23Dec2003
Ge PAW_PBE Ge_d 03Jul2007
H PAW_PBE H 15Jun2001
Hf PAW_PBE Hf_pv 06Sep2000
Hg PAW_PBE Hg 06Sep2000
Ho PAW_PBE Ho_3 06Sep2000
I PAW_PBE I 08Apr2002
In PAW_PBE In_d 06Sep2000
Ir PAW_PBE Ir 06Sep2000
K PAW_PBE K_sv 06Sep2000
Kr PAW_PBE Kr 07Sep2000
La PAW_PBE La 06Sep2000
Li PAW_PBE Li_sv 10Sep2004
Lu PAW_PBE Lu_3 06Sep2000
Mg PAW_PBE Mg_pv 13Apr2007
Mn PAW_PBE Mn_pv 02Aug2007
Mo PAW_PBE Mo_pv 04Feb2005
N PAW_PBE N 08Apr2002
Na PAW_PBE Na_pv 19Sep2006
Nb PAW_PBE Nb_pv 08Apr2002
Nd PAW_PBE Nd_3 06Sep2000
Ne PAW_PBE Ne 05Jan2001
Ni PAW_PBE Ni_pv 06Sep2000
Np PAW_PBE Np 06Sep2000
O PAW_PBE O 08Apr2002
Os PAW_PBE Os_pv 20Jan2003
P PAW_PBE P 06Sep2000
Pa PAW_PBE Pa 07Sep2000
Pb PAW_PBE Pb_d 06Sep2000
Pd PAW_PBE Pd 04Jan2005
Pm PAW_PBE Pm_3 07Sep2000
Pr PAW_PBE Pr_3 07Sep2000
Pt PAW_PBE Pt 04Feb2005
Pu PAW_PBE Pu 06Sep2000
Rb PAW_PBE Rb_sv 06Sep2000
Re PAW_PBE Re_pv 06Sep2000
Rh PAW_PBE Rh_pv 25Jan2005
Ru PAW_PBE Ru_pv 28Jan2005
S PAW_PBE S 06Sep2000
Sb PAW_PBE Sb 06Sep2000
Sc PAW_PBE Sc_sv 07Sep2000
Se PAW_PBE Se 06Sep2000
Si PAW_PBE Si 05Jan2001
Sm PAW_PBE Sm_3 07Sep2000
Sn PAW_PBE Sn_d 06Sep2000
Sr PAW_PBE Sr_sv 07Sep2000
Ta PAW_PBE Ta_pv 07Sep2000
Tb PAW_PBE Tb_3 06Sep2000
Tc PAW_PBE Tc_pv 04Feb2005
Te PAW_PBE Te 08Apr2002
Th PAW_PBE Th 07Sep2000
Ti PAW_PBE Ti_pv 07Sep2000
Tl PAW_PBE Tl_d 06Sep2000
Tm PAW_PBE Tm_3 20Jan2003
U PAW_PBE U 06Sep2000
V PAW_PBE V_sv 02Aug2007
W PAW_PBE W_sv 04Sep2015
Xe PAW_PBE Xe 07Sep2000
Y PAW_PBE Y_sv 25May2007
Yb PAW_PBE Yb 23Dec2003
Zn PAW_PBE Zn 06Sep2000
Zr PAW_PBE Zr_sv 04Jan2005