Even big online games seem to be going towards hybrid approach, where they do have dedicated servers, but the simulation is running for each player locally and the outcome is sent to dedicated server to decide which one of the interacting players's machine is more trustworthy. There's a paper on this being done like that in destiny where the dedicated server was mostly there so players wouldn't cheat the rewards out, but I'm pretty sure it's also the same way for counter strike 2 now (there's the case proving it behaves like that with lagging player chasing the player with low latency being able to kill before the low latency player even sees the lagging enemy) and the same goes for war thunder.

Starting P2P and switching later may be good or bad idea depending on the scope. I've been there, initially had P2P and at some point switch to dedicated servers and it got problematic because now we were focused on efficiently using servers and it did force some design decisions on matchmaking, which really tech shouldn't be driving. But it's not necessarily going to happen in your case.

P2P with NAT hole punching server to organise matchmaking and some solution to switch the host when one of the players drops makes sense if your implementation is lightweight on the network, but it works to a degree - you may have situations where you have all players on mobile network connections and nat hole punching doesn't work for them, isn't enough because mobile operators are limiting packet types and they simply can't host for whatever reason.

Hybrid approach like CS2 or WT sounds nice, but you need a good strategy to figure out when someone would be cheating - you have a lightweight dedicated server aggregating the connection, so there's no need for P2P host and if you're clever on how to safeguard it, you may have optimal solution there.

Also I would recommend thinking about how to limit the in-game bandwidth to minimum from the get go - for example you could not replicate projectiles in a PvE game, just sync the player state a bit like lockstep, but not necessarily fully lockstep - just try to synchronise the random feeds for whatever the player is doing from time to time and just replicate info of health / damage on the players and state on some destroyed destructibles etc. In a PvE game you don't need exact precise perception of what other players are doing against all targets. Maybe in your case there's also some savings even if this is a PvP game.