Can OPNsense allow only a portion of its traffic to go through an external proxy

[cicirrr]

I wanted to try sending just a small part of my traffic through an external proxy (I tested one service like ProxyShare,naproxy,proxylite), mainly for some simple routing tests.
Right now I'm using basic policy routing, but I'm not sure if that's the correct or safest way to do it.
For anyone with more experience:
Is there a recommended method for this?
Should I separate it by device or VLAN?
Anything important a beginner should watch out for?

[viragomann]

Right now I'm using basic policy routing, but I'm not sure if that's the correct or safest way to do it.

It is.
Just ensure that the policy-routing rule is set on the top of the rule set, so that it is checked before other rules allowing any outbound.

Should I separate it by device or VLAN?

I assume, you'd assigned static IPs to the concerned devices, maybe via DHCP. So put all these IPs into an alias and use it as source in the policy-routing rule.
Of course, you can also put all these devices in a separate VLAN if you want. So you don't need the source alias.