Paul discusses in several places in 2 Cor 8–11 matters pertaining to supporting gospel work, gospeling itself, and striving for expanding the opportunities to gospel:

8:18: And we are sending along with him the brother who is praised by all the churches for his service to the gospel.

9:13: Because of the service by which you have proved yourselves, men will
praise God for the obedience that accompanies your confession of the
gospel of Christ, and for your generosity in sharing with them and with
everyone else.

10:12 We
do not dare to classify or compare ourselves with some who commend
themselves. When they measure themselves by themselves and compare
themselves with themselves, they are not wise. 13 We,
however, will not boast beyond proper limits, but will confine our
boasting to the field God has assigned to us, a field that reaches even
to you. 14 We
are not going too far in our boasting, as would be the case if we had
not come to you, for we did get as far as you with the gospel of
Christ. 15 Neither do we go beyond our limits by boasting of work done by others. Our hope is that, as your faith continues to grow, our area of activity among you will greatly expand, 16 so
that we can preach the gospel in the regions beyond you. For we do not
want to boast about work already done in another man’s territory. 17 But, “Let him who boasts boast in the Lord.” 18 For it is not the one who commends himself who is approved, but the one whom the Lord commends.

11:4 For
if someone comes to you and preaches a Jesus other than the Jesus we
preached, or if you receive a different spirit from the one you
received, or a different gospel from the one you accepted, you put up
with it easily enough. 5 But I do not think I am in the least inferior to those “super-apostles.” 6 I may not be a trained speaker, but I do have knowledge. We have made this perfectly clear to you in every way.7 Was it a sin for me to lower myself in order to elevate you by preaching the gospel of God to you free of charge?