can i delpoy to bfs with enemies on it

Radiance rules aren't published yet. This uses the printed card and current rules only, and it isn't a ruling on the new mechanics.

Yes — Deploy's printed permission is only "Play this only to a battlefield," with no "you control" qualifier, so enemy units sitting there don't stop you. Gear normally can only be played to your Base (Rule 149.2), which is exactly why Deploy's permission matters; "only" narrows the destination to a battlefield, it doesn't restrict which battlefield. For support, Bomb's text ("play a Bomb gear token to a battlefield") uses the same unrestricted wording.

Playing it there doesn't Contested the field or stage a showdown — Contested status is applied by Units (Rule 190.3.a.1), not Gear. Do note Deploy isn't Action or Reaction, so from hand this is your Main Phase in an Open state, not mid-showdown.

One thing genuinely unknown: nothing published carves Deploy's Gear out of Rule 149.3 (unattached non-Unit Gear at a battlefield is recalled to its controller's Base during the next cleanup), even though the keyword clearly intends the Gear to stay ("when an opponent holds here, kill this"). This is my interpretation based on Rule 149.2 and the printed [Deploy] reminder text. No official FAQ exists for this specific interaction.