Haibike Xduro AllMtn 3.0 dropper post

[boomdocker]

I have a Haibike Xduro All Mtn 3.0
Need to service the dropper post as it has become sticky
Have taken it out, but it seems to be unbranded so not sure how to go about the service
It has a tiny air valve at the top - I've let the air out, but can't see how i'm going to re-pressure it as its too small to fit a shock pump to
Any ideas?

 

[Jackware]

Presumably on a Haibike it's a XLC or Brand-X clone but my Google fu has only found this regarding the internal thread

Dropper post pressure adapter?

November 8, 2020 - I have a BrandX 27.5 diameter 85mm dropper post, which could do with pressurising. The top of the cartridge is not a Schrader valve, but appears to be a

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