Ich würde in diesem Kontext "offerings" wählen, da es sich offenbar um Angebote "etwas zu tun/zu unternehmen" handelt.

"Offer" eher dann, wenn ein (schriftliches) Angebot über eine bestimmte Sache vorliegt.

Bisschen umständlich, aber ich habe noch einen Knoten in meinen Hirnwindungen.

Andere LEOs wacher? ;)

The services offered and the activities of ...

or even

The services and activities offered ...

I find both "offers" and "offerings" less common.

I agree with DRG with the following changes:

The services and activities offered by this non-profit organization are dedicated to creating human wellbeing on every level.

1. Offering is most commonly (though by no means exlusively) used in a religious sense: "Bring your offering to the altar"; "We give our tithes and offerings to the Lord."

2. "Dedicated to" requires a "noun", i.e. gerundive, rather than infinitive.

3. Wellbeing can be written as one word without the hyphen as well as with the hyphen, your choice.

The original sentence is: Hundreds and thousands of volunteers support the Foundation's offers and activities in over 200 centers across the globe.

It's about a volunteer organization with a spiritual focus, so still "services", "offerings" wouldn't work at all for yoga and mediation programs for example?

If I interpret it correctly, the two sentences should be read together as:

"Hundreds and thousands of volunteers support the Foundation's offers and activities in over 200 centers across the globe. The [offerings/offers?] and activities of this non-profit organization are dedicated to create human well-being on every level."

I would then suggest:

"Hundreds and thousands of volunteers support the Foundation's services and activities in over 200 centers worldwide. This non-profit organization is dedicated to creating human wellbeing on all levels."

The foundation offers services, using the term "offers" as a noun IMHO does not lead to a clearer or better communication.

Hope it helps