For a suggestion, I have one strong suggestion for adding a property: Tensile Strength.
Actually, I would like to make a proposal; I am currently collecting this data for each element in a spreadsheet already.
When it is done, I would like to show it to you along with sources, so you can consider adding the data to the website's element property.

First, I would like to try to demonstrate why specifically Tensile Strength is worthy among countless mechanical properties of materials.
https://en.wikipedia.org/wiki/Strength_of_materials#Stress_parameters_for_resistance
In an introductory material science paper, it focused heavily on Stress–strain curve, and various testing for material strength properties.
Tensile strength is highest in metals out of all materials, so metals are used for their tensile strength in engineering. This makes tensile strength particularly important for metals.
Since metals constitute most of the elements in the periodic table of elements, it would be great to have.
Compressive strength is high in concrete and ceramics, so they are used instead of metals. Fatigue and Impact stress are more complex measurements for specific cases.
https://www.rouloconsulting.com/book-review-material-selection-mechanical-design-fourth-edition/
This link has a strength density chart, and the strength is yield strength, which is tensile strength, so it's a practically useful property in material selection.

To me, tensile strength is a comprehensive measure of strength of a metal. It quickly answers the question of how strong a material is, how much force a material can withstand.
If someone asks a general question, which is stronger Iron vs Titanium? Aluminium vs Copper? To answer that, I would look at Tensile Strength.

https://simple.wikipedia.org/wiki/Tensile_strength
Ultimate tensile strength (UTS, = Tensile Strength) and Yield strength (without deformity).
Obtained from a tensile testing result: Stress–strain curve.
https://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve
Here from the stress-strain curve, Young's Modulus (=Modulus of Elasticity) can also be obtained. It's listed as one of the properties in Ptable.

Mechanical properties in the website currently listed cannot tell how much force (technically stress) it can withstand before material deforms or breaks.
Young's Modulus (=Modulus of Elasticity), measures stiffness.
Shear Modulus (G) can be derived from Young's Modulus(E) and Poisson ratio (v) , G = E / 2(1+v),
Bulk Modulus, measures compressibility.
Hardness. measures mechanical indentation or abrasion.

None of these can tell us how much force the metal can carry, how strong it is in terms of how much force it can take until it breaks.
I believe tensile strength is the most practical and informative of all mechanical properties, while being simple and not so complicated.
It's just a dumb force (stress), a direct measurement, not something that needs to be calculated like modulus (stress / strain), so it's closer to pure science than moduluses.

If you are interested in adding it to Ptable, but have a trusted source of data that you would rather use, I would be happy to collect the data from there rather than from random sites on the internet.
Otherwise I can find the data for Tensile strength around the internet like here. I am collecting data for my personal use anyways.
http://www.matweb.com/search/MaterialGroupSearch.aspx

I would be thrilled to see Tensile Strength listed in the Ptable.
Please tell me your thoughts.