Is AGPL-3.0 compatible with GPL-2.0-only?
No.
AGPL is v3-based; GPLv2-only has no upgrade path to reach it.
General guidance, not legal advice.
Obligations when redistributing as open source
No obligations checklist — this combination cannot be distributed as a single work.
Other distribution models
The verdict is the same under every distribution model; the obligations differ. Check this pair in the tool to switch models.