Since it turns out that last login isn’t really a reliable metric to track (cf. Last Login Date is available on Usage dashboards. Any chance we can get this in our apps?), I’ll approcah this question from a slightly different angle 
I’m not a PostHog expert, but from what I’ve seen, this kind of analysis isn’t available natively.
That’s said, it’s fairly easy to build your own using SQL (technically HogQL cf. Introducing HogQL: Direct SQL access for PostHog - PostHog). You can query the latest event captured for each user, which givs you a solid last seen timestamp. It’s not the exact login time, but it’s clide enought for most needs.
-- Basic example: get the latest activity timestamp per user
SELECT
person_id,
max(timestamp) AS last_activity
FROM events
GROUP BY person_id
ORDER BY last_activity DESC
LIMIT 100
Glide also offers several built-in ito track user behaviour which might better match your needs depending on your context. You might want to explore:
- Google Analytics & Tag Manager
- Koala
- Mixpanel
- PostHog
- Segment
More details available here: https://www.glideapps.com/integrations 